Most industrial applications of synthetic diamond have long been associated with their hardness; this property makes diamond the ideal material for machine tools and cutting tools. As the hardest known naturally occurring material, diamond can be used to polish, cut, or wear away any material, including other diamonds. Common industrial applications of this ability include diamond-tipped drill bits and saws, and the use of diamond powder as an abrasive. These are by far the largest industrial applications of synthetic diamond. While natural diamond is also used for these purposes, synthetic HPHT diamond is more popular, mostly because of better reproducibility of its mechanical properties.
Machining and cutting tools
Synthetic diamond
Synthetic diamond | Machining and cutting tools
Machine tools and cutting tools; as a Thermal conductor; as an Optical material; semiconductors ; gemstones As gemstones Sorry. I cannot find the answer based on the context. As radiation detection device
when was the first man made diamond made
user
1954
assistant
what are the materials required to make this?
user
Pure carbon, the belt press, the cubic press and the split-sphere (BARS) press.
assistant
what temperature-pressure conditions are required fopr this?
user
High pressure, high temperature.
assistant
can you mention any of its uses?
user
Diamond is not suitable for machining ferrous alloys at high speeds, as carbon is soluble in iron at the high temperatures created by high-speed machining, leading to greatly increased wear on diamond tools compared to alternatives. The usual form of diamond in cutting tools is micron-sized grains dispersed in a metal matrix (usually cobalt) sintered onto the tool. This is typically referred to in industry as polycrystalline diamond (PCD). PCD-tipped tools can be found in mining and cutting applications. For the past fifteen years, work has been done to coat metallic tools with CVD diamond, and though the work shows promise, it has not significantly replaced traditional PCD tools.
Synthetic diamond | Machining and cutting tools
Most industrial applications of synthetic diamond have long been associated with their hardness; this property makes diamond the ideal material for machine tools and cutting tools. As the hardest known naturally occurring material, diamond can be used to polish, cut, or wear away any material, including other diamonds. Common industrial applications of this ability include diamond-tipped drill bits and saws, and the use of diamond powder as an abrasive. These are by far the largest industrial applications of synthetic diamond. While natural diamond is also used for these purposes, synthetic HPHT diamond is more popular, mostly because of better reproducibility of its mechanical properties.
Synthetic diamond | Machining and cutting tools
In the HPHT method, there are three main press designs used to supply the pressure and temperature necessary to produce synthetic diamond: the belt press, the cubic press and the split-sphere (BARS) press. Diamond seeds are placed at the bottom of the press. The internal part of press is heated above 1400 °C and melts the solvent metal. The molten metal dissolves the high purity carbon source, which is then transported to the small diamond seeds and precipitates, forming a large synthetic diamond. The original GE invention by Tracy Hall uses the belt press wherein the upper and lower anvils supply the pressure load to a cylindrical inner cell.
Synthetic diamond | High pressure, high temperature
Diamond is not suitable for machining ferrous alloys at high speeds, as carbon is soluble in iron at the high temperatures created by high-speed machining, leading to greatly increased wear on diamond tools compared to alternatives.
Diamond | Industrial-grade diamonds
There are several methods used to produce synthetic diamonds. The original method uses high pressure and high temperature (HPHT) and is still widely used because of its relatively low cost. The process involves large presses that can weigh hundreds of tons to produce a pressure of 5 GPa at 1500 °C. The second method, using chemical vapor deposition (CVD), creates a carbon plasma over a substrate onto which the carbon atoms deposit to form diamond. Other methods include explosive formation (forming detonation nanodiamonds) and sonication of graphite solutions.
Synthetic diamond | Manufacturing technologies
Polycrystalline diamond (PCD) is formed in a large High Temperature-High Pressure (HT-HP) press, as either a diamond wafer on a backing of carbide, or forming a "vein" of diamond within a carbide wafer or rod. Most wafers are polished to a mirror finish, then cut with an electrical discharge machining (EDM) tool into smaller, workable segments that are then brazed onto the sawblade, reamer, drill, or other tool. Often they are EDM machined and/or ground an additional time to expose the vein of diamond along the cutting edge. These tools are mostly used for the machining of nonmetallic and nonferrous materials.
Diamond tool | PCD cutting tools
The cubic press was created shortly thereafter to increase the volume to which pressure could be applied. A cubic press is typically smaller than a belt press and can more rapidly achieve the pressure and temperature necessary to create synthetic diamond. However, cubic presses cannot be easily scaled up to larger volumes: the pressurized volume can be increased by using larger anvils, but this also increases the amount of force needed on the anvils to achieve the same pressure. An alternative is to decrease the surface area to volume ratio of the pressurized volume, by using more anvils to converge upon a higher-order platonic solid, such as a dodecahedron.
Synthetic diamond | High pressure, high temperature
For best possible quality natural diamonds are used as single-point cutting elements during the final stages of the machining process. A CNC SPDT lathe rests atop a high-quality granite base with micrometer surface finish quality. The granite base is placed on air suspension on a solid foundation, keeping its working surface strictly horizontal. The machine tool components are placed on top of the granite base and can be moved with high degree of accuracy using a high-pressure air cushion or hydraulic suspension. The machined element is attached to an air chuck using negative air pressure and is usually centered manually using a micrometer.
Diamond turning | The machine tool
Used in machine tools for machining ceramics and high speed aluminium.
Diamond tool | PCD tool insert
Diamond tools are suitable to process the following materials: As diamonds can react with Fe, Co, Ni, Cr, V under the high temperatures generated in the grinding processes, normally diamond tools are not suitable to process steels, including common steels and various tough alloy steels, while the other superhard tool, cubic boron nitride (CBN) tool, is suitable to process steels. The tools made with common abrasives (e.g. corundum and silicon carbide) can also do the task.
Diamond tool | Applicable materials
Alternative methods of diamond machining in practice also include diamond fly cutting and diamond milling. Diamond fly cutting can be used to generate diffraction gratings and other linear patterns with appropriately contoured diamond shapes. Diamond milling can be used to generate aspheric lens arrays by annulus cutting methods with a spherical diamond tool.
Diamond turning | The machine tool
There is a growing body of peer-reviewed theoretical work on synthesizing diamond by mechanically removing/adding hydrogen atoms and depositing carbon atoms (a process known as diamond mechanosynthesis or DMS). For example, the 2006 paper in this continuing research effort by Freitas, Merkle and their collaborators reports that the most-studied mechanosynthesis tooltip motif (DCB6Ge) successfully places a C carbon dimer on a C(110) diamond surface at both 300 K (room temperature) and 80 K (liquid nitrogen temperature), and that the silicon variant (DCB6Si) also works at 80 K but not at 300 K. These tooltips are intended to be used only in carefully controlled environments (e.g., vacuum).
Mechanosynthesis | Diamond mechanosynthesis
Single point diamond turning (SPDT) utilizes a solid, flawless diamond as the cutting edge. The single crystalline diamond can be natural or synthetic, and is sharpened to the desired dimensions by mechanical grinding and polishing. The cutting edge of most diamond tools is sharp to tens of nanometers, making it very effective for cutting non-ferrous materials with high resolution. SPDT is a very accurate machining process, used to create finished aspherical and irregular optics without the need for further polishing after completion. The most accurate machine tool in the world, the LODTM, formerly at Lawrence Livermore National Laboratory, had a profile accuracy estimated at 28 nm, while most machines seek a roughness within that deviation.
Diamond tool | Single point diamond turning tools
Used in turning centers for optics and precision surfaces.
Diamond tool | PD tool insert
Recent advances in the HPHT and CVD synthesis techniques have improved the purity and crystallographic structure perfection of single-crystalline diamond enough to replace silicon as a diffraction grating and window material in high-power radiation sources, such as synchrotrons. Both the CVD and HPHT processes are also used to create designer optically transparent diamond anvils as a tool for measuring electric and magnetic properties of materials at ultra high pressures using a diamond anvil cell.
Synthetic diamond | Optical material
Diamond turning is turning using a cutting tool with a diamond tip. It is a process of mechanical machining of precision elements using lathes or derivative machine tools (e.g., turn-mills, rotary transfers) equipped with natural or synthetic diamond-tipped tool bits. The term single-point diamond turning (SPDT) is sometimes applied, although as with other lathe work, the "single-point" label is sometimes only nominal (radiused tool noses and contoured form tools being options). The process of diamond turning is widely used to manufacture high-quality aspheric optical elements from crystals, metals, acrylic, and other materials. Plastic optics are frequently molded using diamond turned mold inserts.
Diamond turning | Introduction
The chuck itself is separated from the electric motor that spins it by another air suspension. The cutting tool is moved with sub-micron precision by a combination of electric motors and piezoelectric actuators. As with other CNC machines, the motion of the tool is controlled by a list of coordinates generated by a computer. Typically, the part to be created is first described using a CAD model, then converted to G-code using a CAM program, and the G-code is then executed by the machine control computer to move the cutting tool. The final surface is achieved with a series of cutting passes of decreasing depth.
Diamond turning | The machine tool
However, such a press would be complex and difficult to manufacture. The BARS apparatus is claimed to be the most compact, efficient, and economical of all the diamond-producing presses. In the center of a BARS device, there is a ceramic cylindrical "synthesis capsule" of about 2 cm in size. The cell is placed into a cube of pressure-transmitting material, such as pyrophyllite ceramics, which is pressed by inner anvils made from cemented carbide (e.g., tungsten carbide or VK10 hard alloy). The outer octahedral cavity is pressed by 8 steel outer anvils. After mounting, the whole assembly is locked in a disc-type barrel with a diameter about 1 meter.
Synthetic diamond | High pressure, high temperature
Synthetic diamonds are produced via high pressure, high temperature (HPHT) or chemical vapor deposition (CVD) technology. These diamonds have numerous industrial and commercial uses including cutting tools, thermal conductors and consumer diamond gemstones.
List of synthetic diamond manufacturers | Introduction
This helps explain why 80% of mined diamonds (equal to about 100 million carats or 20 tonnes annually) are unsuitable for use as gemstones and known as "bort", are destined for industrial use. In addition to mined diamonds, synthetic diamonds found industrial applications almost immediately after their invention in the 1950s; another 400 million carats (80 tonnes) of synthetic diamonds are produced annually for industrial use, which is nearly four times the mass of natural diamonds mined over the same period. The dominant industrial use of diamond is cutting, drilling (drill bits), grinding (diamond edged cutters), and polishing. Most uses of diamonds in these technologies do not require large diamonds; in fact, most diamonds that are not gem-quality can find an industrial use.
Allotropes of carbon | Diamond
The barrel is filled with oil, which pressurizes upon heating, and the oil pressure is transferred to the central cell. The synthesis capsule is heated up by a coaxial graphite heater and the temperature is measured with a thermocouple.
Synthetic diamond | High pressure, high temperature
Diamond tools are used in the following domains: Besides what are listed above, there are also other domains where diamond tools are applied, for example, in medicine, Venezuelan scientist Humberto Fernandez Moran invented the diamond knife for use in delicate surgeries in 1955. Apart from its use as an abrasive due to its high hardness, diamond is also used to make other products for its many other good properties such as high heat-conductivity, low friction coefficient, high chemical stability, high resistivity and high optical performances. These applications include coatings on bearings and CDs, acting as lens and thermistors, making high-voltage switches and sensors, etc.
Diamond tool | Applied domains
The grinding operation is combined with EDM for several reasons. For example, according to Modern Machine Shop, the combination allows a higher material removal rate and is therefore more cost effective. Also, the EDM process slightly affects the surface finish. Grinding is used on the affected area to provide a finer final surface. The Beijing Institute of Electro-Machining attributes a finer shaping and surface geometry to the combination of the two processes into one.
Diamond tool | PCD cutting tools
He left GE in 1955, and three years later developed a new apparatus for the synthesis of diamond—a tetrahedral press with four anvils—to avoid violating a U.S. Department of Commerce secrecy order on the GE patent applications.
Synthetic diamond | GE diamond project
If categorized by use, there are diamond grinding tools, diamond cutting tools (e.g., diamond coated twist drill bits), diamond drilling tools, diamond sawing tools (e.g., diamond saw blades), diamond drawing dies, etc.
Diamond tool | Categories by use
This internal pressure is confined radially by a belt of pre-stressed steel bands. The anvils also serve as electrodes providing electric current to the compressed cell. A variation of the belt press uses hydraulic pressure, rather than steel belts, to confine the internal pressure. Belt presses are still used today, but they are built on a much larger scale than those of the original design. The second type of press design is the cubic press. A cubic press has six anvils which provide pressure simultaneously onto all faces of a cube-shaped volume. The first multi-anvil press design was a tetrahedral press, using four anvils to converge upon a tetrahedron-shaped volume.
Synthetic diamond | High pressure, high temperature
The patent that issued after the decision was U.S. Patent 4,344,142, "Direct digital control of rubber molding presses." The patent includes 11 method claims, three of which are independent. All method claims relate to molding of physical articles. The only diagrams in the patent are flowcharts. There are no diagrams of machinery. As the dissenting opinion in "Diehr" noted, the patent specification "teaches nothing about the chemistry of the synthetic rubber-curing process, nothing about the raw materials to be used in curing synthetic rubber, nothing about the equipment to be used in the process, and nothing about the significance or effect of any process variable such as temperature, curing time, particular compositions of material, or mold configurations."
Diamond v. Diehr | The patent no 3591.978
Although high speed tool steel has been used in the past it is quickly being replaced by carbide, ceramic, or diamond tooling. Because carbide inserts are long lasting and easily replaced, they lend themselves to high production. Ceramic tools are brittle but can withstand high temperatures. This makes high speed machining possible. Diamond tools are used to achieve a superior surface finish (though they can only be used on non-ferrous materials).
Arbor milling | Tooling Materials
The company developed five generations of plasma reactor designs using software simulations of plasma physics to develop its technology for managing a high-density plasma for diamond growth at extremely high temperatures. As contrasted with diamond simulants (which are non-diamond material that appears similar to diamond) and natural mined diamonds, synthetic diamonds are actual diamonds that are produced by a manufacturing process. The company "grows" diamond using the chemical vapor deposition (CVD) method, by placing a small piece of natural diamond in a plasma reactor for a period of about two weeks. The resulting man-made diamond is essentially identical to natural diamond (atomically, molecularly, chemically, visually, in terms of hardness, optical brilliance, crystalline structure, etc.) but without the resource intensiveness, hazards, and environmental concerns that occur with diamond mining.
Diamond Foundry | Technology
Stellite soon joined high speed steels as a material for single-point cutters. Although diamond turning had been around for a long time, it was not until these new, expensive metals came about that the idea of cutting inserts became commonly applied in machining. Before this, most single-point cutters were forged entirely of tool steel (then ground at the tip). Now it became more common to attach a separate tip (of one material) to a holder (of another). With the development of commercially available cemented carbide (1920s) and ceramic inserts (post-WWII), this trend accelerated, because carbide and ceramic are even more expensive and even less suited to serving as a shank.
Tool bit | History
Optical elements produced by the means of diamond turning are used in optical assemblies in telescopes, video projectors, missile guidance systems, lasers, scientific research instruments, and numerous other systems and devices. Most SPDT today is done with computer numerical control (CNC) machine tools. Diamonds also serve in other machining processes, such as milling, grinding, and honing. Diamond turned surfaces have a high specular brightness and require no additional polishing or buffing, unlike other conventionally machined surfaces.
Diamond turning | Introduction
Diamond turning is most often used for making infrared optics, because at longer wavelengths optical performance is less sensitive to surface finish quality, and because many of the materials used are difficult to polish with traditional methods. Temperature control is crucial, because the surface must be accurate on distance scales shorter than the wavelength of light. Temperature changes of a few degrees during machining can alter the form of the surface enough to have an effect. The main spindle may be cooled with a liquid coolant to prevent temperature deviations. The diamonds that are used in the process are incredibly strong in the vertical downward direction but very weak in the upward and sideways directions.
Diamond turning | Process
Diamond turning is specifically useful when cutting materials that are viable as infrared optical components and certain non-linear optical components such as potassium dihydrogen phosphate (KDP). KDP is a perfect material in application for diamond turning, because the material is very desirable for its optical modulating properties, yet it is impossible to make optics from this material using conventional methods. KDP is water-soluble, so conventional grinding and polishing techniques are not effective in producing optics. Diamond turning works well to produce optics from KDP. Generally, diamond turning is restricted to certain materials. Materials that are readily machinable include: The most often requested materials that are not readily machinable are:
Diamond turning | Materials
Diamonds are embedded in drill tips or saw blades, or ground into a powder for use in grinding and polishing applications (due to its extraordinary hardness). Specialized applications include use in laboratories as containment for high pressure experiments (see diamond anvil), high-performance bearings, and limited use in specialized windows of technical apparatuses.
Allotropes of carbon | Diamond
The inventors, respondents, filed a patent application for a "[process] for molding raw, uncured synthetic rubber into cured precision products." The process of curing synthetic rubber depends on a number of factors including time, temperature and thickness of the mold. Using the Arrhenius equation formula_1 which may be restated as "ln"("v") = "CZ" + "x" it is possible to calculate when to open the press and to remove the cured, molded rubber. The problem was that there was, at the time the invention was made, no disclosed way to obtain an accurate measure of the temperature without opening the press.
Diamond v. Diehr | The problem and its solution
A diamond tool is a cutting tool with diamond grains fixed on the functional parts of the tool via a bonding material or another method. As diamond is a superhard material, diamond tools have many advantages as compared with tools made with common abrasives such as corundum and silicon carbide.
Diamond tool | Introduction
In 1941, an agreement was made between the General Electric (GE), Norton and Carborundum companies to further develop diamond synthesis. They were able to heat carbon to about under a pressure of for a few seconds. Soon thereafter, the Second World War interrupted the project. It was resumed in 1951 at the Schenectady Laboratories of GE, and a high-pressure diamond group was formed with Francis P. Bundy and H. M. Strong. Tracy Hall and others joined the project later. The Schenectady group improved on the anvils designed by Percy Bridgman, who received a Nobel Prize for his work in 1946.
Synthetic diamond | GE diamond project
According to their manufacturing methods or bond types, diamond tools can be categorized to the following way:
Diamond tool | Categories by manufacturing method
Over 100,000 CPU hours were invested in this latest study. The DCB6 tooltip motif, initially described by Merkle and Freitas at a Foresight Conference in 2002, was the first complete tooltip ever proposed for diamond mechanosynthesis and remains the only tooltip motif that has been successfully simulated for its intended function on a full 200-atom diamond surface. The tooltips modeled in this work are intended to be used only in carefully controlled environments (e. g., vacuum). Maximum acceptable limits for tooltip translational and rotational misplacement errors are reported in Peng et al. (2006) -- tooltips must be positioned with great accuracy to avoid bonding the dimer incorrectly.
Molecular nanotechnology | Existing work on diamond mechanosynthesis
In the late 1970s, General Electric pioneered the technology of polycrystalline diamond compacts (PDCs) as a replacement for natural diamonds in drill bits. PDCs have been used to cut through crystalline rock surfaces for extended periods of time in lab environments, and these capabilities have now been implemented in harsh environments throughout the world. As of August 2000, the U.S. Department of Energy claimed that nearly one-third of the total footage drilled worldwide is being drilled with PDC bits, with a claimed savings of nearly $100,000 per PDC bit as compared to roller-core bits.
Diamond tool | Polycrystalline diamond compacts
Diamond can be used to make grinding tools, which have following advantages:
Diamond tool | Advantages of diamond grinding tools
For economic reasons, the growth of most synthetic diamonds is terminated when they reach a mass of to .
Synthetic diamond | Later developments
Diamond turning is a multi-stage process. Initial stages of machining are carried out using a series of CNC lathes of increasing accuracy. A diamond-tipped lathe tool is used in the final stages of the manufacturing process to achieve sub-nanometer level surface finishes and sub-micrometer form accuracies. The surface finish quality is measured as the peak-to-valley distance of the grooves left by the lathe. The form accuracy is measured as a mean deviation from the ideal target form. Quality of surface finish and form accuracy is monitored throughout the manufacturing process using such equipment as contact and laser profilometers, laser interferometers, optical and electron microscopes.
Diamond turning | Process
There are thousands of kinds of diamond tools. They can be categorized by their manufacturing methods and their uses.
Diamond tool | Categories
The product is always rich in graphite and other non-diamond carbon forms and requires prolonged boiling in hot nitric acid (about 1 day at 250 °C) to dissolve them. The recovered nanodiamond powder is used primarily in polishing applications. It is mainly produced in China, Russia and Belarus and started reaching the market in bulk quantities by the early 2000s.
Synthetic diamond | Detonation of explosives
Most materials with high thermal conductivity are also electrically conductive, such as metals. In contrast, pure synthetic diamond has high thermal conductivity, but negligible electrical conductivity. This combination is invaluable for electronics where diamond is used as a heat sink for high-power laser diodes, laser arrays and high-power transistors. Efficient heat dissipation prolongs the lifetime of those electronic devices, and the devices' high replacement costs justify the use of efficient, though relatively expensive, diamond heat sinks. In semiconductor technology, synthetic diamond heat spreaders prevent silicon and other semiconducting devices from overheating.
Synthetic diamond | Thermal conductor
The high-pressure synthesis of diamond in 1953 in Sweden and in 1954 in the US, made possible by the development of new apparatus and techniques, became a milestone in synthesis of artificial superhard materials. The synthesis clearly showed the potential of high-pressure applications for industrial purposes and stimulated growing interest in the field. Four years after the first synthesis of artificial diamond, cubic boron nitride c-BN was obtained and found to be the second hardest solid. Synthetic diamond can exist as a single, continuous crystal or as small polycrystals interconnected through the grain boundaries. The inherent spatial separation of these subunits causes the formation of grains, which are visible by the unaided eye due to the light absorption and scattering properties of the material.
Superhard material | Synthetic diamond
Borazon has a number of uses , such as: cutting tools, dies, punches, shears, knives, saw blades, bearing rings, needles, rollers, spacers, balls, pump, compressor parts, engine & drive train components (e.g. camshafts, crankshafts, gears, valve stems, drive shafts, CV joints, piston pins, fuel injectors, turbochargers, and aerospace and land-based gas turbine parts such as vanes, blades, nozzles, and seals), surgical knives, blades, scissors, honing, superfinishing, cylinder liners, connecting rods, grinding of steel and paper mill rolls, and gears. Prior to the production of Borazon, diamond was the preferred abrasive used for grinding very hard superalloys but it could not be used effectively on steels because carbon tends to dissolve in iron at high temperatures.
Borazon | Uses and production
Diamond is an allotrope of carbon where the atoms are arranged in a modified version of face-centered cubic ("fcc") structure known as "diamond cubic". It is known for its hardness (see table above) and incompressibility and is targeted for some potential optical and electrical applications. The properties of individual natural diamonds or carbonado vary too widely for industrial purposes, and therefore synthetic diamond became a major research focus.
Superhard material | Diamond
Hollow steel tube with diamond tipped segments for drilling holes through concrete walls in the construction industry, porcelain tiles or granite worktops in the domestic industry, or also used for sample core extractions in the mining industry.
Diamond tool | Diamond tipped core bit or holesaw
Despite all the automation involved in the diamond turning process, the human operator still plays the main role in achieving the final result. Quality control is a major part of the diamond turning process and is required after each stage of machining, sometimes after each pass of the cutting tool. If it is not detected immediately, even a minute error during any of the cutting stages results in a defective part. The extremely high requirements for quality of diamond-turned optics leave virtually no room for error. The SPDT manufacturing process produces a relatively high percentage of defective parts, which must be discarded.
Diamond turning | Quality control
Diamonds however are held mechanically, or with low-melting point tin-lead solder, since the resultant heat generated by friction can be extreme and won't allow the use of thermal adhesives.
Gemcutter | Equipment of Faceting
Carbon nitride is only stable at a pressure that is higher than that of the graphite-to-diamond transformation. The synthesis conditions would require extremely high pressures because carbon is four- and sixfold coordinated. In addition, CN would pose problems of carbide formation if they were to be used to machine ferrous metals. Although publications have reported preparation of CN at lower pressures than stated, synthetic CN was not proved superhard.
Superhard material | Carbon nitride
Typically used on hand grinders for grinding concrete or stone.
Diamond tool | Diamond tipped grinding cups
Diamond is hard, chemically inert, and has high thermal conductivity and a low coefficient of thermal expansion. These properties make diamond superior to any other existing window material used for transmitting infrared and microwave radiation. Therefore, synthetic diamond is starting to replace zinc selenide as the output window of high-power CO lasers and gyrotrons. Those synthetic polycrystalline diamond windows are shaped as disks of large diameters (about 10 cm for gyrotrons) and small thicknesses (to reduce absorption) and can only be produced with the CVD technique. Single crystal slabs of dimensions of length up to approximately 10 mm are becoming increasingly important in several areas of optics including heatspreaders inside laser cavities, diffractive optics and as the optical gain medium in Raman lasers.
Synthetic diamond | Optical material
His breakthrough was using a "belt" press, which was capable of producing pressures above and temperatures above . The press used a pyrophyllite container in which graphite was dissolved within molten nickel, cobalt or iron. Those metals acted as a "solvent-catalyst", which both dissolved carbon and accelerated its conversion into diamond. The largest diamond he produced was across; it was too small and visually imperfect for jewelry, but usable in industrial abrasives. Hall's co-workers were able to replicate his work, and the discovery was published in the major journal "Nature". He was the first person to grow a synthetic diamond with a reproducible, verifiable and well-documented process.
Synthetic diamond | GE diamond project
Diamond is one of the hardest natural materials on earth; much harder than corundum and silicon carbide. Diamond also has high strength, good wear resistance, and a low friction coefficient. So when used as an abrasive, it has many obvious advantages over many other common abrasives.
Diamond tool | Advantages
Vacuum brazed diamond saws are manufactured by brazing synthetic diamond particles to the outside edge of the circular saw blade in a vacuum brazing furnace. All of the diamond particles are on the exterior cutting edge of the blade, with no metal-diamond mixture. Depending on the manufacturer's recommended blade application, vacuum brazed blades will cut a wide variety of material including concrete, masonry, steel, various irons, plastic, tile, wood and glass. Finer synthetic diamond grits will reduce the chipping of tile and burring of steel and provide a smoother finish. Larger diamond grits will provide a higher cutting speed, but will be more likely to cause chipping, burring, or cracking.
Diamond blade | Vacuum brazing
SPDT is used for optics, for flat surfaces where both surface finish and unusually high dimensional accuracy are required, and when lapping would be uneconomical or impractical.
Diamond tool | Single point diamond turning tools
However, diamond has several limitations for mass industrial application, including its high cost and oxidation at temperatures above 800 °C. In addition, diamond dissolves in iron and forms iron carbides at high temperatures and therefore is inefficient in cutting ferrous materials including steel. Therefore, recent research of superhard materials has been focusing on compounds which would be thermally and chemically more stable than pure diamond. The search for new superhard materials has generally taken two paths. In the first approach, researchers emulate the short, directional covalent carbon bonds of diamond by combining light elements like boron, carbon, nitrogen, and oxygen.
Superhard material | Introduction
Maximum acceptable limits for tooltip translational and rotational misplacement errors are reported in paper III—tooltips must be positioned with great accuracy to avoid bonding the dimer incorrectly. Over 100,000 CPU hours were invested in this study. The DCB6Ge tooltip motif, initially described at a Foresight Conference in 2002, was the first complete tooltip ever proposed for diamond mechanosynthesis and remains the only tooltip motif that has been successfully simulated for its intended function on a full 200-atom diamond surface. Although an early paper gives a predicted placement speed of 1 dimer per second for this tooltip, this limit was imposed by the slow speed of recharging the tool using an inefficient recharging method and is not based on any inherent limitation in the speed of use of a charged tooltip.
Mechanosynthesis | Diamond mechanosynthesis
Additionally, no sensing means was proposed for discriminating among the three possible outcomes of an attempted dimer placement—deposition at the correct location, deposition at the wrong location, and failure to place the dimer at all—because the initial proposal was to position the tooltip by dead reckoning, with the proper reaction assured by designing appropriate chemical energetics and relative bond strengths for the tooltip-surface interaction. More recent theoretical work analyzes a complete set of nine molecular tools made from hydrogen, carbon and germanium able to (a) synthesize all tools in the set (b) recharge all tools in the set from appropriate feedstock molecules and (c) synthesize a wide range of stiff hydrocarbons (diamond, graphite, fullerenes, and the like).
Mechanosynthesis | Diamond mechanosynthesis
Bundy and Strong made the first improvements, then more were made by Hall. The GE team used tungsten carbide anvils within a hydraulic press to squeeze the carbonaceous sample held in a catlinite container, the finished grit being squeezed out of the container into a gasket. The team recorded diamond synthesis on one occasion, but the experiment could not be reproduced because of uncertain synthesis conditions, and the diamond was later shown to have been a natural diamond used as a seed. Hall achieved the first commercially successful synthesis of diamond on December 16, 1954, and this was announced on February 15, 1955.
Synthetic diamond | GE diamond project
Diamond has compressive yield strength of 130–140GPa. This exceptionally high value, along with the hardness and transparency of diamond, are the reasons that diamond anvil cells are the main tool for high pressure experiments. These anvils have reached pressures of . Much higher pressures may be possible with nanocrystalline diamonds.
Diamond | Yield strength
Wire with diamond crystals for cutting. Some of the features of Diamond Wire Cutting are: Non-percussive, fumeless and quiet Smooth cutting face Unlimited cutting depth Horizontal, vertical and angled cutting of circular openings up to 2500mm diameter Plunge cutting facility which allows blind and rebated openings to be formed Remote controlled operation for increased safety
Diamond tool | Diamond wire cutting
Within the category of industrial diamonds, there is a sub-category comprising the lowest-quality, mostly opaque stones, which are known as bort. Industrial use of diamonds has historically been associated with their hardness, which makes diamond the ideal material for cutting and grinding tools. As the hardest known naturally occurring material, diamond can be used to polish, cut, or wear away any material, including other diamonds. Common industrial applications of this property include diamond-tipped drill bits and saws, and the use of diamond powder as an abrasive. Less expensive industrial-grade diamonds, known as bort, with more flaws and poorer color than gems, are used for such purposes.
Diamond | Industrial-grade diamonds
Diamond pastes are used for polishing materials that require a mirror finish. They are often used in metallurgical specimens, carbide dies, carbide seals, spectacle glass industry, and for polishing diamonds. Diamond paste is mainly used in industrial requirements for polishing and sharpening metal blades and other metal surfaces. The paste is not just to polish the metal blade but sharpen the cutting edge as well.
Diamond tool | Diamond paste and <a href="slurry">slurry</a>
Used in so-called diamond anvil experiments to create high-pressure environments, diamonds are able to withstand crushing pressures in excess of 600 gigapascals (6 million atmospheres).
Material properties of diamond | Pressure resistance
Diamond tools, though for cutting, are often abrasive in nature.
Abrasive | Coated abrasives
This can make better use of the diamonds and prolong the diamond tool's service life. The grit (size), hardness and concentration of the diamonds in the diamond segments should also be considered. For example, when the material to be cut is soft, the diamonds' size can be big, hardness can be medium, and concentration should be a little bit higher. This combination can get good cutting efficiency, and at the same time prolong the blade's life. When the material is hard, the diamonds' size should be small, hardness should be high, and concentration can be a little bit lower.
Diamond segment | Use
Some of the diamond finishers were technically gifted and strove to improve the tools used for working diamonds. The "Pfälzer Doppen", also called the "Amann-Doppen", a kind of dop developed and patented by Philipp Amann in 1928 that is still used today, was best at meeting the demands of the trade and became the standard everywhere. In all the world's countries in which diamonds are cut and polished, machines from the firm Amann are in use. In 1929, Brücken alone had 45 diamond-cutting shops with 375 employees. All together, the Western Palatinate had 108 diamond-cutting shops with 679 employees. In this same year, of course, came the onset of the Great Depression, and along with it came the beginning of the end for the diamond-cutting industry.
Brücken, Kusel | Economic structure
Diamond Machining Technology was established in 1976, as a manufacturer of large diamond grinding and polishing wheels for industrial applications. Due to increased overseas competition, DMT looked for ways to diversify its business. After much testing and development work, a prototype sharpener was developed, which the engineers at DMT then refined to an unbreakable, clean-cutting diamond honing tool. The first polka dot diamond bench stones were soon thereafter shipped to customers such as Brookstone for use in the woodworking area and Bloomingdale's for use in the kitchen. The new sharpener quickly found its way to other sectors as well, such as the automotive, marine, and aviation industries.
Acme United Corporation | DMT
Applications of DLC typically utilize the ability of the material to reduce abrasive wear. Tooling components, such as endmills, drill bits, dies and molds often use DLC in this manner. DLC is also used in the engines of modern supersport motorcycles, Formula 1 racecars, NASCAR vehicles, and as a coating on hard-disk platters and hard-disk read heads to protect against head crashes. Virtually all of the multi-bladed razors used for wet shaving have the edges coated with hydrogen-free DLC to reduce friction, preventing abrasion of sensitive skin. It is also being used as a coating by some weapon manufacturers/custom gunsmiths.
Diamond-like carbon | Applications
Industrial grade diamond knives are used to slice hard materials such as bone, teeth and plant matter for both light microscopy and for electron microscopy. Gem quality diamond knives are used for slicing thin sections for electron microscopy. Microtomy is a method for the preparation of thin sections for materials such as bones, minerals and teeth, and an alternative to electropolishing and ion milling. Microtome sections can be made thin enough to section a human hair across its breadth, with section thickness between 50 nm and 100 μm.
Microtome | Introduction
CVD can be used to produce a synthetic diamond by creating the circumstances necessary for carbon atoms in a gas to settle on a substrate in crystalline form. CVD of diamonds has received much attention in the materials sciences because it allows many new applications that had previously been considered too expensive. CVD diamond growth typically occurs under low pressure (1–27 kPa; 0.145–3.926 psi; 7.5–203 Torr) and involves feeding varying amounts of gases into a chamber, energizing them and providing conditions for diamond growth on the substrate. The gases always include a carbon source, and typically include hydrogen as well, though the amounts used vary greatly depending on the type of diamond being grown.
Chemical vapor deposition | Diamond
The similar atomic sizes of boron, carbon and nitrogen, as well as the similar structures of carbon and boron nitride polymorphs, suggest that it might be possible to synthesize diamond-like phase containing all three elements. It is also possible to make compounds containing B-C-O, B-O-N, or B-C-O-N under high pressure, but their synthesis would expect to require a complex chemistry and in addition, their elastic properties would be inferior to that of diamond. Beginning in 1990, a great interest has been put in studying the possibility to synthesize dense B-C-N phases. They are expected to be thermally and chemically more stable than diamond, and harder than c-BN, and would therefore be excellent materials for high speed cutting and polishing of ferrous alloys.
Superhard material | Boron carbon nitride
There is a growing body of peer-reviewed theoretical work on synthesizing diamond by mechanically removing/adding hydrogen atoms and depositing carbon atoms (a process known as mechanosynthesis). This work is slowly permeating the broader nanoscience community and is being critiqued. For instance, Peng et al. (2006) (in the continuing research effort by Freitas, Merkle and their collaborators) reports that the most-studied mechanosynthesis tooltip motif (DCB6Ge) successfully places a C carbon dimer on a C(110) diamond surface at both 300 K (room temperature) and 80 K (liquid nitrogen temperature), and that the silicon variant (DCB6Si) also works at 80 K but not at 300 K.
Molecular nanotechnology | Existing work on diamond mechanosynthesis
Typically, diamond is formed by heating carbon at very high temperatures (>5,000 K) and pressures (>120,000 atmospheres). However, Narayan and his group used kinetics and time control of pulsed nanosecond laser melting to overcome thermodynamic limitations and create a supercooled state that enables conversion of carbon into Q-carbon and diamond at ambient temperatures and pressures. The process uses a high-powered laser pulse, similar to that used in eye surgery, lasting approximately 200 nanoseconds. This raises the temperature of the carbon to approximately 4,000 K (3,700 °C; 6,700 °F) at atmospheric pressure. The resulting liquid is then quenched (rapidly cooled); it is this stage that is the source of the "Q" in the material's name.
Amorphous carbon | Production
Diamond powder deposited through electroplating is used to make files (including nail files) and in small grinding applications.
Diamond tool | Diamond electroplated tools
Thermoplastics are difficult to machine because they have poor thermal conductivity. This creates heat that builds up in the cutting zone, which degrades the tool life and locally melts the plastic. Once the plastic melts, it just flows around the cutting edge instead of being removed by it. Machinability can be improved by using high lubricity coolant and keeping the cutting area free of chip build up. Composites often have the worst machinability because they combine the poor thermal conductivity of a plastic resin with the tough or abrasive qualities of the fiber (glass, carbon etc.) material. The machinability of rubber and other soft materials improves by using a very low temperature coolant, such as liquid carbon dioxide.
Machinability | Other materials
This increases the forces involved in machining and for this reason hard materials are usually not recommended for light machinery. Heat treated materials, on the other side, are usually much tougher and have no problem holding a sharp edge without chipping under less favourable conditions (like under vibration). This makes them adequate for hand tools and light machines.
Reamer | Tool materials
The wide band gap of diamond (5.5 eV) gives it excellent dielectric properties. Combined with the high mechanical stability of diamond, those properties are being used in prototype high-power switches for power stations. Synthetic diamond transistors have been produced in the laboratory. They remain functional at much higher temperatures than silicon devices, and are resistant to chemical and radiation damage. While no diamond transistors have yet been successfully integrated into commercial electronics, they are promising for use in exceptionally high-power situations and hostile non-oxidizing environments. Synthetic diamond is already used as radiation detection device. It is radiation hard and has a wide bandgap of 5.5 eV (at room temperature).
Synthetic diamond | Electronics
The increase in lifetime of articles coated with DLC that wear out because of abrasion can be described by the formula "f = (g)", where "g" is a number that characterizes the type of DLC, the type of abrasion, the substrate material and μ is the thickness of the DLC coating in μm. For "low-impact" abrasion (pistons in cylinders, impellers in pumps for sandy liquids, etc.), "g" for pure "ta-C" on 304 stainless steel is 66. This means that one-μm thickness (that is ≈5% of the thickness of a human hair-end) would increase service lifetime for the article it coated from a week to over a year and two-μm thickness would increase it from a week to 85 years.
Diamond-like carbon | Environmental benefits of durable products
Many blades are designed to operate either wet or dry. However, diamond tools and blades work better when wet, and dry cutting should be limited to situations in which water cannot or should not be used. Water will prevent the blade from overheating, greatly reduce the amount of harmful dust created by cutting, remove the slurry from the cut, and extend the life of the blade, since diamond is unable to withstand the forces involved at the elevated temperatures involved in dry cutting ceramic and abrasive materials, and will be subject to rapid tool wear and possible failure. When water cannot be used (in, for example, electrical saws), measures should be taken to ensure that the operator does not inhale the dust created by the process, which can cause silicosis, a serious lung disease.
Diamond blade | Cutting with or without water
A diamond anvil cell (DAC) is a high-pressure device used in geology, engineering, and materials science experiments. It enables the compression of a small (sub-millimeter-sized) piece of material to extreme pressures, typically up to around 100–200 gigapascals, although it is possible to achieve pressures up to 770 gigapascals (7,700,000 bars or 7.7 million atmospheres). The device has been used to recreate the pressure existing deep inside planets to synthesise materials and phases not observed under normal ambient conditions. Notable examples include the non-molecular ice X, polymeric nitrogen and metallic phases of xenon and potentially hydrogen. A DAC consists of two opposing diamonds with a sample compressed between the polished culets (tips).
Diamond anvil cell | Introduction
Then, put the grinding wheels into sintering furnaces to sinter without press.
Diamond grinding cup wheel | Manufacturing methods
Because ultrasonic vibration machining is driven by microchipping or erosion mechanisms, the material removal rate of metals can be slow and the sonotrode tip can wear down quickly from the constant impact of abrasive particles on the tool. Moreover, drilling deep holes in parts can prove difficult as the abrasive slurry will not effectively reach the bottom of the hole. Note, rotary ultrasonic machining is efficient at drilling deep holes in ceramics because the absence of a slurry cutting fluid and the cutting tool is coated in harder diamond abrasives. In addition, ultrasonic vibration machining can only be used on materials with a hardness value of at least 45 HRC.
Ultrasonic machining | Disadvantages
As machining is a subtractive process, the time to remove the material is a major factor in determining the machining cost. The volume and shape of the material to be removed as well as how fast the tools can be fed will determine the machining time. When using milling cutters, the strength and stiffness of the tool which is determined in part by the length to diameter ratio of the tool will play the largest role in determining that speed. The shorter the tool is relative to its diameter the faster it can be fed through the material. A ratio of 3:1 (L:D) or under is optimum.
Design for manufacturability | Design and shape
Further research to consider additional tooltips will require time-consuming computational chemistry and difficult laboratory work.
Molecular nanotechnology | Existing work on diamond mechanosynthesis
If that ratio cannot be achieved, a solution like this depicted here can be used. For holes, the length to diameter ratio of the tools are less critical, but should still be kept under 10:1. There are many other types of features which are more or less expensive to machine. Generally chamfers cost less to machine than radii on outer horizontal edges. 3D interpolation is used to create radii on edges that are not on the same plane which incur 10X the cost. Undercuts are more expensive to machine. Features that require smaller tools, regardless of L:D ratio, are more expensive.
Design for manufacturability | Design and shape
The hardness of synthetic diamond (70–150 GPa) is very dependent on the relative purity of the crystal itself. The more perfect the crystal structure, the harder the diamond becomes. It has been reported that HPHT single crystals and nanocrystalline diamond aggregates (aggregated diamond nanorods) can be harder than natural diamond.
Superhard material | Synthetic diamond
Remaining non-diamond inclusions are removed through laser drilling and filling of the voids produced.
Diamond | Cutting
In fact this property has been exploited to study atom-by-atom wear at the nanoscale in DLC.
Diamond-like carbon | Distinction from natural and synthetic diamond
Cutting tool materials must be harder than the material which is to be cut, and the tool must be able to withstand the heat and force generated in the metal-cutting process. Also, the tool must have a specific geometry, with clearance angles designed so that the cutting edge can contact the workpiece without the rest of the tool dragging on the workpiece surface. The angle of the cutting face is also important, as is the flute width, number of flutes or teeth, and margin size. In order to have a long working life, all of the above must be optimized, plus the speeds and feeds at which the tool is run.
Cutting tool (machining) | Introduction
The majority of commercially available synthetic diamonds are yellow and are produced by so-called "high-pressure high-temperature" (HPHT) processes. The yellow color is caused by nitrogen impurities. Other colors may also be reproduced such as blue, green or pink, which are a result of the addition of boron or from irradiation after synthesis. Another popular method of growing synthetic diamond is chemical vapor deposition (CVD). The growth occurs under low pressure (below atmospheric pressure). It involves feeding a mixture of gases (typically to hydrogen) into a chamber and splitting them to chemically active radicals in a plasma ignited by microwaves, hot filament, arc discharge, welding torch or laser.
Diamond | Synthetics
High mechanical strain causes brittle failure in the diamond grains, and ductile failure in the matrix. The diamond grains give the alloy a degree of surface texture; when a smooth surface is desired, the alloy can be plated and polished. In 1996, the price for a 10×10×0.1 cm substrate was quoted as USD 200.
Dymalloy | Introduction
He suggested that most diamonds that had been produced up to that point were likely synthetic spinel.
Synthetic diamond | History
Charcoal is used as a drawing material in artwork, barbecue grilling, iron smelting, and in many other applications. Wood, coal and oil are used as fuel for production of energy and heating. Gem quality diamond is used in jewelry, and industrial diamonds are used in drilling, cutting and polishing tools for machining metals and stone. Plastics are made from fossil hydrocarbons, and carbon fiber, made by pyrolysis of synthetic polyester fibers is used to reinforce plastics to form advanced, lightweight composite materials.
Carbon | Applications
Every diamond contains atoms other than carbon in concentrations detectable by analytical techniques. Those atoms can aggregate into macroscopic phases called inclusions. Impurities are generally avoided, but can be introduced intentionally as a way to control certain properties of the diamond. Growth processes of synthetic diamond, using solvent-catalysts, generally lead to formation of a number of impurity-related complex centers, involving transition metal atoms (such as nickel, cobalt or iron), which affect the electronic properties of the material. For instance, pure diamond is an electrical insulator, but diamond with boron added is an electrical conductor (and, in some cases, a superconductor), allowing it to be used in electronic applications.
Synthetic diamond | Impurities and inclusions
In the traditional method the temperature of the mold press, which was apparently set at a fixed temperature and was controlled by thermostat, fluctuated due to the opening and closing of the press. The invention solved this problem by using embedded thermocouples to constantly check the temperature, and then feeding the measured values into a computer. The computer then used the Arrhenius equation to calculate when sufficient energy had been absorbed so that the molding machine should open the press.
Diamond v. Diehr | The problem and its solution