I. New developments in binder raw materials 1. The particle size of ultrafine iron powder refining metal powder plays an important role in activating sintering, reducing the sintering temperature of the product, improving the holding strength of the bonding agent on diamond, improving the processing efficiency and service life of the product. . Carbonyl iron powder has long been used, but its cost is still high, and it is not very economical for some applications with heavy efficiency requirements. The problem arises by the appearance of ultrafine iron powder having an average Fibonacci® particle size of 1.8 to 2.0 μm and a sintering temperature of less than 900 °C.
2. Pre-alloying powder metal powder pre-alloying is beneficial to prevent premature loss and segregation of low melting point metals in the metal bond product during sintering, improve the compactness, uniformity, elastic limit and yield strength of the sintered product, and enhance the diamond Hold the ability and lower the sintering temperature. In recent years, metal powder prealloying technology has attracted attention. For example, geological diamond drill bits made of Cu-Zn-Ni and Cu-Ni-Mn prealloyed powders have a 99% and 45% increase in service life and processing efficiency compared to non-prealloyed powder drills, respectively.
3. Ultra-fine toughened polyimide resin powder Compared with phenolic resin, polyimide resin has high bonding strength, high heat resistance temperature (above 50 °C), and the life of the grinding wheel is more than doubled under dry grinding conditions. However, the polyimide resin has poor toughness, low bending strength and high cost, which limits its popularization and application to a certain extent. In order to change this situation, an ultrafine toughened polyimide resin powder with an average particle size of 30-40 μm and a curing temperature of 230 ° C and a toughening modification was developed, which is resistant to bending compared with ordinary polyimide resin. The strength is increased by 23% and the compressive strength is increased by 20%.
Second, the new progress in the study of binding agents 1, ceramic bonding agent Low-temperature sintering, high-strength ceramic bonding agent has always been one of the themes of the industry, the research results in recent years are gratifying:
(1) The ceramic bond applied to the 80m/s CBN grinding wheel has been put into practical use;
(2) Ceramic bond applied to 120m/s CBN grinding wheel has been successfully developed;
(3) Ceramic bond abrasives used in the processing of cemented carbide tools, diamond composite sheets, magnetic materials, and engineering ceramics have also been successfully developed;
(4) In order to give full play to the advantages of ceramic binders with pores, the control of pores was realized, and the effect of pore-forming agents on the properties of ceramic binders was investigated. The research shows that the strength of the abrasive obtained by adding graphite is affected by the shape of the graphite particles, the amount of addition, the sintering temperature, and the strength of the abrasive decreases with the addition of the abrasive. The strength of the abrasive obtained by adding CaC03 is high, and the pores are generated. The shape is mostly spherical and evenly distributed. The pore size increases with the increase of the amount within the allowable range, and the pore-forming effect of CaCO3 is better than that of graphite.
2, sintered metal bond China is a country with poor metal cobalt, so the study of "iron to cobalt" is another hot spot in the research of diamond tools in China. In order to improve the performance of iron-based binders, the application of rare earth elements La and Ce has received much attention in recent years. The study on the addition of rare earth elements by doping method shows that the iron-based diamond tools developed by this method have nearly or slightly exceeded the cobalt-based diamonds without rare earths in terms of flexural strength, impact toughness, porosity and hardness. The corresponding indicator for the tool. The study of adding rare earth elements in the form of mixed rare earths shows that the flexural strength and impact toughness of the carcass materials are increased by 12.4% and 16.6%, respectively, while the hardness is only increased by 3.2%. Refining, the carcass is more tightly bonded to the diamond, the height of the diamond blade is greatly increased, and the service life is increased by more than 24%.
3. Electroplated metal bond is similar to sintered metal bond. The application of rare earth elements in electroplated products also attracts attention: the study of rare earth elements added to Ni-Co plating solution in the form of chloride shows that the prepared carcass material pores Significantly reduced, the hardness is significantly improved, the coating dispersion ability is increased by more than 12%, the deep plating ability is increased by more than 20%, and the plating speed is greatly improved.
At the same time, research on low-cobalt electroplating formulations has also made progress. The study of replacing Ni-Co with Ni-Co-Mn shows that the content of Co in the plating solution is reduced from the conventional 30% to 5%, and about 0.1% is added. Mn, the hardness and strength of the coating are higher than that of Ni-Co, and the toughness is significantly reduced. The electroplated diamond tool used for gem carving is sharper and more durable than Ni-Co, and the manufacturing cost is lowered.
2. Pre-alloying powder metal powder pre-alloying is beneficial to prevent premature loss and segregation of low melting point metals in the metal bond product during sintering, improve the compactness, uniformity, elastic limit and yield strength of the sintered product, and enhance the diamond Hold the ability and lower the sintering temperature. In recent years, metal powder prealloying technology has attracted attention. For example, geological diamond drill bits made of Cu-Zn-Ni and Cu-Ni-Mn prealloyed powders have a 99% and 45% increase in service life and processing efficiency compared to non-prealloyed powder drills, respectively.
3. Ultra-fine toughened polyimide resin powder Compared with phenolic resin, polyimide resin has high bonding strength, high heat resistance temperature (above 50 °C), and the life of the grinding wheel is more than doubled under dry grinding conditions. However, the polyimide resin has poor toughness, low bending strength and high cost, which limits its popularization and application to a certain extent. In order to change this situation, an ultrafine toughened polyimide resin powder with an average particle size of 30-40 μm and a curing temperature of 230 ° C and a toughening modification was developed, which is resistant to bending compared with ordinary polyimide resin. The strength is increased by 23% and the compressive strength is increased by 20%.
Second, the new progress in the study of binding agents 1, ceramic bonding agent Low-temperature sintering, high-strength ceramic bonding agent has always been one of the themes of the industry, the research results in recent years are gratifying:
(1) The ceramic bond applied to the 80m/s CBN grinding wheel has been put into practical use;
(2) Ceramic bond applied to 120m/s CBN grinding wheel has been successfully developed;
(3) Ceramic bond abrasives used in the processing of cemented carbide tools, diamond composite sheets, magnetic materials, and engineering ceramics have also been successfully developed;
(4) In order to give full play to the advantages of ceramic binders with pores, the control of pores was realized, and the effect of pore-forming agents on the properties of ceramic binders was investigated. The research shows that the strength of the abrasive obtained by adding graphite is affected by the shape of the graphite particles, the amount of addition, the sintering temperature, and the strength of the abrasive decreases with the addition of the abrasive. The strength of the abrasive obtained by adding CaC03 is high, and the pores are generated. The shape is mostly spherical and evenly distributed. The pore size increases with the increase of the amount within the allowable range, and the pore-forming effect of CaCO3 is better than that of graphite.
2, sintered metal bond China is a country with poor metal cobalt, so the study of "iron to cobalt" is another hot spot in the research of diamond tools in China. In order to improve the performance of iron-based binders, the application of rare earth elements La and Ce has received much attention in recent years. The study on the addition of rare earth elements by doping method shows that the iron-based diamond tools developed by this method have nearly or slightly exceeded the cobalt-based diamonds without rare earths in terms of flexural strength, impact toughness, porosity and hardness. The corresponding indicator for the tool. The study of adding rare earth elements in the form of mixed rare earths shows that the flexural strength and impact toughness of the carcass materials are increased by 12.4% and 16.6%, respectively, while the hardness is only increased by 3.2%. Refining, the carcass is more tightly bonded to the diamond, the height of the diamond blade is greatly increased, and the service life is increased by more than 24%.
3. Electroplated metal bond is similar to sintered metal bond. The application of rare earth elements in electroplated products also attracts attention: the study of rare earth elements added to Ni-Co plating solution in the form of chloride shows that the prepared carcass material pores Significantly reduced, the hardness is significantly improved, the coating dispersion ability is increased by more than 12%, the deep plating ability is increased by more than 20%, and the plating speed is greatly improved.
At the same time, research on low-cobalt electroplating formulations has also made progress. The study of replacing Ni-Co with Ni-Co-Mn shows that the content of Co in the plating solution is reduced from the conventional 30% to 5%, and about 0.1% is added. Mn, the hardness and strength of the coating are higher than that of Ni-Co, and the toughness is significantly reduced. The electroplated diamond tool used for gem carving is sharper and more durable than Ni-Co, and the manufacturing cost is lowered.
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