Improve the quality of China's diamond tools from the craft

The survey results show that China's total stone output, stone export volume and stone consumption have reached the world's first place: there are more than 20,000 stone processing enterprises, nearly 5 million employees, with an annual output of 6 million cubic meters of stone, with an annual output of 120 million square meters. Rice, with an annual output value of more than 80 billion yuan, has more than 500 advanced production lines, and imports and exports totaling more than 1.2 billion US dollars, becoming a veritable stone production country. China is also a large ceramics producing country. In 1999, the total output of various types of ceramic tiles was 1.6 billion square meters (33.6% of the world's total output), and the total consumption was 1.3 billion square meters (30.8% of the world's total consumption). There are more than 1,000 diamond and diamond tool manufacturers. In 1999, the annual output of diamonds exceeded 750 million carats, making it a major diamond producer. Diamond saw blades have been able to meet domestic demand. Nearly one-third of the products are exported, forming a certain competitive strength in the DIY market. Although China has entered the ranks of major powers in the above aspects, it is not yet a strong country. With the integration of the global economy and China's entry into the WTO, how to make China a powerful country in the production of diamond tools is an important issue facing our counterparts. According to our practice and investigation, we only put forward some views on improving the quality of diamond tools in China. 1. Providing high-strength diamond diamonds with stable mass production, coarse particles and good thermal stability for diamond tool manufacturing. Grade quality, particle size and concentration have a decisive effect on diamond tools. In China's diamond synthesis, the six-sided top small tonnage high-strength process has matured, the six-face top large tonnage large cavity process has been continuously improved, and the two-side top synthetic diamond has also begun to take shape. The powder catalyst synthesis, carbon, and pyrophyllite block raw materials are continuously produced. perfect. Therefore, for the manufacture of diamond tools in China, high-strength diamond with stable performance, coarse particles and good thermal stability is possible. Foreign diamond companies, in addition to the SDA+, SDB, DSN, MBS, ISD series, DeBeers launched BKI, BK30, BK60, BK70 diamonds for the Chinese market, South Korea's Rijin company launched six-sided synthetic SDS series diamonds, all worthy of China Learn from peers. 2. Using strong carbide forming elements to improve diamond holding force A key factor in improving the cutting efficiency and life of diamond saw blades is to increase the holding power of the carcass to diamond. The carcass has a good grip on the diamond, the diamond will not fall off prematurely, and has the largest protruding height, sharp cutting and high efficiency. There are generally three ways to improve the diamond holding power: (1) Improve the mechanical holding power. This is because the metal powder shrinks during sintering, forming a compressive stress to hold the diamond. The compressive stress is generated due to the difference in thermal expansion coefficient between diamond and the carcass metal, which is caused by volume change during sintering or crystal formation and growth. Due to the limited yield strength of the carcass, the resulting compressive stress and mechanical holding force are limited. (2) Adding a small amount of strong carbide forming elements such as Cr, W, Mo, etc. to the powder, because of its good wettability and affinity for diamond, carbides are formed at the interface between diamond and the carcass metal during sintering to achieve diamond The combination of sub-gold is conducive to strengthening and improving the holding power. (3) The surface of the diamond is plated with a layer of strong carbides to form metal elements such as Cr, Ni, Ti, W, and the like. This is a process that has been adopted in recent years. To this end, Yanshan University has specially developed and produced three types of vacuum micro-evaporation titanium plating equipment. According to the experimental research and use at home and abroad, the most effective conditions and scope of diamond plating technology are: 1 Applicable to high grade diamond, the effect is more obvious; 2 The order of improvement of holding power in pure diamond matrix is: Cr plating>Ti plating>Uncoated diamond. 3MBS-960Cr2 chrome diamond is suitable for Co-based carcass, low-iron low-bronze carcass and WC carcass. 4MBS-960Ti2 titanium-plated diamond is suitable for drilling bronze-based carcass and iron-based carcass. 5 Tungsten-plated diamond is used in cutting asphalt, concrete concrete (GreenConcrete) and reinforced (reinforced steel) saw blades. 6 nickel-plated diamond is suitable for resin bond grinding wheel, and its effect is as follows: needle-shaped nickel-plated diamond > nickel-plated diamond > unnickel-plated diamond. 7 Silver-plated diamond is suitable for grinding precision resin bond grinding wheels for tungsten carbide cemented carbide tools. Because the price of silver is not very expensive, it is suitable for high-precision grinding, and its thermal conductivity is good, suitable for oil-cooled grinding of hard alloys. At the same time, silver is a good lubricant, which can reduce the friction between the grinding wheel and the workpiece, and the heat is not large. The plating of strong carbide forming elements such as Ti, Ni, W, Cr, etc. improves the diamond holding power, mainly due to: 1 plating metal can prevent oxidation, graphitization and iron of diamond under certain temperature, pressure and sintering time conditions. Thermal erosion. The author carried out TG (thermogravimetric) analysis on different metal-plated diamonds and found that diamond began to lose weight and graphitize at around 800 °C. When diamonds such as Ti, W, and TiN are plated at 900 ° C, 925 ° C, and 940 ° C, weight loss and graphitization begin. It shows that the diamond is coated with metal to prevent oxidation and graphitization, and can withstand thermal shock and thermal decomposition. It has obvious protective effect on high temperature sintered carcass. 2The plated strong carbide element can form a carbide alloy at the interface between the diamond and the carcass under sintering conditions, which is beneficial to the chemical bonding and metallurgical bonding between the diamond and the carcass metal, greatly improving the holding force of the carcass on the diamond, and the tungsten plating X-ray analysis of the diamond revealed that a WC phase had formed on the diamond surface. 3 can increase the static pressure of diamond by 5% to 20%. 4 diamond plating metal can improve the friction of diamond, while the latter helps to increase the holding power. 3. Using ultrafine powder and prealloyed powder In the production of special saw blades, ultrafine metal powder and prealloyed powder should be used. The refinement of the metal powder is advantageous for lowering the sintering temperature and increasing the hardness. The use of pre-alloyed powder prevents premature loss and segregation of low-melting metals, favors the elastic limit and yield strength of sintered products, increases the holding power of diamonds, and reduces sintering temperature and holding time. China Shanghai Materials Institute, Beijing Artificial Crystal Institute, Changsha Metallurgical Materials Institute and Central South University of Technology Powder and Metallurgical Institute have done a lot of work in this regard. South Korea's ultra-fine powders and pre-alloyed powders from BASF, UM, INCO, Fum-tungstene, and Kennametal are widely used in the production of high-grade saw blades. 4. Promote granulation process in the production of cutter head The granulation process has been widely used in the production of cemented carbide and ceramics in China. In recent years, it has also been widely used and developed in the production of diamond cutter heads. The advantage of powder granulation is that the segregation of diamond is reduced, the distribution is more uniform, the cutting performance of the cutter head is improved, the fluidity of the powder is increased, the application of the volumetric cold press process is made possible, and the ordinary cold press process is better, reducing The harm of dust to workers. The disadvantage is that investment and process procedures are added, and binders are added during granulation, which may have an adverse effect on welding, sintering and carcass performance.