The emergence of new ceramic tools is the first new technological achievement for mankind to reform mechanical cutting by using ceramic materials. As early as the beginning of the 20th century, Germany and the United Kingdom had begun to seek to replace traditional carbon steel tools with ceramic tools. Ceramic materials have become a new generation of tool materials due to their high hardness and high temperature resistance. However, ceramics are also limited by their well-known brittleness. Therefore, how to overcome the brittleness of ceramic tool materials and improve its toughness has become a ceramic for nearly a hundred years. The main subject of tool research. The range of applications for ceramics is also growing.
The main reasons for the engineering technology industry to develop and promote ceramic knives are (1) to greatly improve production efficiency; and (2) to be determined by the depletion of tungsten resources, the main component of high-speed steel and cemented carbide, on a global scale. It was estimated in the early 1990s that the world's proven tungsten resources were only used for 50 years. Tungsten is the most scarce resource in the world, but its consumption in cutting tool materials is very large, which leads to the rising price of tungsten ore, which has risen many times in several decades. This has also promoted the development of ceramic tools to a certain extent. Promotion, the development of ceramic tool materials has achieved remarkable results.
So far, the materials used as ceramic knives have formed alumina ceramics, alumina-metal ceramics, alumina-carbide ceramics, alumina-carbide cermets, alumina-nitride cermets and the latest research success. Boron nitride ceramics, and silicon nitride ceramic tools and other materials. As far as the world is concerned, German ceramic tools have not only been used in ordinary machine tools, but have been used as an efficient, stable and reliable tool for digital control machine tool processing and automated production lines; Japanese ceramic blades are in terms of product type, output and quality. With international advanced level; the United States has always been a world leader in the development of oxide-carbide-nitride ceramic tools. Many achievements have been made in the development and application of Chinese ceramic tools.
1. Alumina ceramic cutter: Pure Al2O3 is used in the material. The additive is beneficial to strengthen the flexural strength of Al2O3, but the high temperature performance is reduced, so it is better to use pure alumina ceramic material.
Al2O3 ceramics have higher room temperature hardness and high temperature hardness than cemented carbide materials. Although the flexural strength of Al2O3 ceramics is low at room temperature, its flexural strength decreases less as the temperature rises during use. It is quite suitable for high speed cutting based on this characteristic. Al2O3 ceramics have good compressive strength at room temperature and high temperature, and can overcome the disadvantages of deformation and collapse of the high-speed steel cutter and carbide cutting blade. In addition, Al2O3 ceramics can be used in physical thermal properties and resistance to oxidation, adhesion and chemical inertness. However, alumina ceramic cutters are more prone to bond wear and notch wear when cutting iron alloys and steel parts. As the longest used tool material, alumina ceramic tools are ideal for cutting hard and brittle metal materials such as chilled cast iron or hardened steel at high speeds; for cutting large parts and for cutting high precision parts. Processing. Alumina ceramic cutters are inferior in short-cutting, small-part, intermittent cutting of steel and single-material materials such as Mg, Al, Ti and Be, and their alloy materials. It is easy to cause diffusion wear or spalling and chipping of the tool. Such defects are the ointment.
2. Alumina-metal ceramics: In order to improve the toughness of Al2O3 ceramic tools, less than 10% of metal elements such as Cr, CO, MO, W, Ti, Fe are introduced into the material, thereby forming Al2O3 cermet, so that the material density and resistance Strong bending strength and hardness are improved. However, due to the low creep strength of the alumina-cermet tool, the oxidation resistance is poor, and the promotion is not good.
3. Alumina-carbide ceramics: A certain proportion of carbides, such as MO2C, WC, TiC, TaC, NbC and Cr3C2, are added to the Al2O3 ceramics to improve the performance of the Al2O3 ceramic tool. When the TiC content is 30%, the durability of the ceramic tool is significantly improved, and the depth of the thermal crack is also small. At present, the international production of hot-pressed Al2O3-TiC ceramic tools adopts this formula. The bending strength and thermal shock resistance of Al2O3—TiC ceramics are better than those of Al2O3 ceramic tools.
4. Alumina-carbide cermet cutter: It is made of Al2O3-TiC ceramic material, which uses MO, Ni (or CO, W) and other metals as the ceramic tool material which is hot pressed by the binder phase. Due to the skeleton of the metal-bonded Al2O3 grains and the carbide grains interpenetrating each other, the joint strength is high, so that good cutting performance is formed. These ceramic tools are best suited for the processing of hardened steel, alloy steel, manganese steel, chilled cast iron, cast steel, nickel-based or chromium alloys, nickel-based and cobalt-based funds. It can also be used for cutting non-metallic materials such as fiberglass, plastic sandwich and ceramic materials. Since alumina-carbide cermet has good thermal shock resistance, it can be used for milling, planing, repeated short cutting or other intermittent cutting, and can also be used for wet cutting with cutting fluid.
5. Alumina-nitride cermet: The basic properties and processing range of this ceramic tool material are comparable to those of Al2O3-carbide cermet material, but it has better thermal shock resistance due to the substitution of carbide for nitride. And more suitable for new cutting. However, its flexural strength and hardness are lower than those of TiC-added cermets, and its research and in-depth development are still continuing.
6. Boron Nitride Ceramic Cutter: Recently, Sumitomo Electric Co., Ltd. developed a ceramic tool material with higher hardness—adhesive cubic boron nitride ceramic (CBN) sintered body. The sintered material is prepared by sintering at a pressure of 7 to 80 Pa at an ultrahigh temperature and high pressure of 2,300 to 2,400 ° C for 10 minutes. This technology also includes unique software technologies such as grinding fine powder diameters to improve CBN purity during the raw material preparation stage. A sintered boron nitride ceramic material having a CBN content of 100% is developed by combining fine particles having a particle diameter of 0.5 mm or less.
Ceramic tools made of boron nitride material do not suffer from common thermal cracking and chipping at the tip end of the tool when cutting hard steel with very high hardness. According to different conditions, the use time of boron nitride ceramic tools can be extended by more than 10 times compared with CBN sintered bodies containing other bonding materials, and it can be used as a material for interrupted cutting. Especially in the automotive industry, hBN sintered bodies are widely used in machining as cutting materials for machining hard cast iron materials such as engines.
Since the prior sintered body contains a particulate binder, it cannot form a unique property such as hardness and thermal conductivity as high as CBN. For example, CBN direct conversion technology is not suitable for high-speed cutting tools because its granularity is too coarse.
7, silicon nitride ceramic tools: silicon nitride ceramic tools have low density, high strength, high hardness physical properties. Its room temperature hardness value has exceeded the hardness of the best cemented carbide tool, which greatly improves its cutting ability and wear resistance, and can process all kinds of hard steel and hardened cast iron with high hardness. Its flexural strength has exceeded that of high-speed and is comparable to ordinary cemented carbide. The fracture toughness value of silicon nitride ceramic tools is 6~7mpaVm better than other series of tools. The thermal resistance index of silicon nitride ceramic tools is as high as 600-800 °C, which is obviously superior to other series of ceramic tools (300-400 °C), and its cutting speed is also 3 to 10 times higher than that of cemented carbide tools. Therefore, in the processing of high-strength intermittent parts, it shows its superior performance.
Silicon nitride ceramic tools include: pure silicon nitride ceramic tools and silicon nitride composite ceramic tools.
1 pure silicon nitride ceramic cutter, its hardness HRA91～92, bending strength 700～900Mpa, fracture toughness 4.2～5.2MpaVm, heat resistance up to 1300～1400°C, its thermal expansion coefficient is 3.0×10-6/°C, Has good antioxidant properties. 2 silicon nitride composite ceramic cutter; it is a ceramic tool made by adding a composition of Al2O3, Y2O3, TiC, TiN and MgO to a silicon nitride matrix, and using a composite strengthening effect and cold pressing sintering, the performance of which is superior to that of hot pressing. Pure silicon nitride ceramic tool.
For example, the addition of Al2O3 sintered ceramic tools to silicon nitride, combined with the characteristics of Al2O3 and SiN4, is higher than that of hard alloy tools and alumina ceramic tools, and the cutting edge temperature is higher than 1000 °C. Its biggest advantage is to increase the cutting speed, increase the feed rate, increase the metal removal rate and extend the tool life. Silicon nitride ceramic tools are particularly suitable for cutting a variety of cast irons and superalloys, but can not process steels that produce long chips.
All in all, with the deepening of the research and development of special ceramic materials, the proportion of ceramic tools in the metal cutting and processing industry has been expanding. With the development requirements of the aerospace and aerospace industries, it is necessary to meet the requirements for improving the cutting efficiency of workpiece materials such as Ti alloys and Ni-based superalloys, and special ceramic tool materials will make greater contributions.
The main reasons for the engineering technology industry to develop and promote ceramic knives are (1) to greatly improve production efficiency; and (2) to be determined by the depletion of tungsten resources, the main component of high-speed steel and cemented carbide, on a global scale. It was estimated in the early 1990s that the world's proven tungsten resources were only used for 50 years. Tungsten is the most scarce resource in the world, but its consumption in cutting tool materials is very large, which leads to the rising price of tungsten ore, which has risen many times in several decades. This has also promoted the development of ceramic tools to a certain extent. Promotion, the development of ceramic tool materials has achieved remarkable results.
So far, the materials used as ceramic knives have formed alumina ceramics, alumina-metal ceramics, alumina-carbide ceramics, alumina-carbide cermets, alumina-nitride cermets and the latest research success. Boron nitride ceramics, and silicon nitride ceramic tools and other materials. As far as the world is concerned, German ceramic tools have not only been used in ordinary machine tools, but have been used as an efficient, stable and reliable tool for digital control machine tool processing and automated production lines; Japanese ceramic blades are in terms of product type, output and quality. With international advanced level; the United States has always been a world leader in the development of oxide-carbide-nitride ceramic tools. Many achievements have been made in the development and application of Chinese ceramic tools.
1. Alumina ceramic cutter: Pure Al2O3 is used in the material. The additive is beneficial to strengthen the flexural strength of Al2O3, but the high temperature performance is reduced, so it is better to use pure alumina ceramic material.
Al2O3 ceramics have higher room temperature hardness and high temperature hardness than cemented carbide materials. Although the flexural strength of Al2O3 ceramics is low at room temperature, its flexural strength decreases less as the temperature rises during use. It is quite suitable for high speed cutting based on this characteristic. Al2O3 ceramics have good compressive strength at room temperature and high temperature, and can overcome the disadvantages of deformation and collapse of the high-speed steel cutter and carbide cutting blade. In addition, Al2O3 ceramics can be used in physical thermal properties and resistance to oxidation, adhesion and chemical inertness. However, alumina ceramic cutters are more prone to bond wear and notch wear when cutting iron alloys and steel parts. As the longest used tool material, alumina ceramic tools are ideal for cutting hard and brittle metal materials such as chilled cast iron or hardened steel at high speeds; for cutting large parts and for cutting high precision parts. Processing. Alumina ceramic cutters are inferior in short-cutting, small-part, intermittent cutting of steel and single-material materials such as Mg, Al, Ti and Be, and their alloy materials. It is easy to cause diffusion wear or spalling and chipping of the tool. Such defects are the ointment.
2. Alumina-metal ceramics: In order to improve the toughness of Al2O3 ceramic tools, less than 10% of metal elements such as Cr, CO, MO, W, Ti, Fe are introduced into the material, thereby forming Al2O3 cermet, so that the material density and resistance Strong bending strength and hardness are improved. However, due to the low creep strength of the alumina-cermet tool, the oxidation resistance is poor, and the promotion is not good.
3. Alumina-carbide ceramics: A certain proportion of carbides, such as MO2C, WC, TiC, TaC, NbC and Cr3C2, are added to the Al2O3 ceramics to improve the performance of the Al2O3 ceramic tool. When the TiC content is 30%, the durability of the ceramic tool is significantly improved, and the depth of the thermal crack is also small. At present, the international production of hot-pressed Al2O3-TiC ceramic tools adopts this formula. The bending strength and thermal shock resistance of Al2O3—TiC ceramics are better than those of Al2O3 ceramic tools.
4. Alumina-carbide cermet cutter: It is made of Al2O3-TiC ceramic material, which uses MO, Ni (or CO, W) and other metals as the ceramic tool material which is hot pressed by the binder phase. Due to the skeleton of the metal-bonded Al2O3 grains and the carbide grains interpenetrating each other, the joint strength is high, so that good cutting performance is formed. These ceramic tools are best suited for the processing of hardened steel, alloy steel, manganese steel, chilled cast iron, cast steel, nickel-based or chromium alloys, nickel-based and cobalt-based funds. It can also be used for cutting non-metallic materials such as fiberglass, plastic sandwich and ceramic materials. Since alumina-carbide cermet has good thermal shock resistance, it can be used for milling, planing, repeated short cutting or other intermittent cutting, and can also be used for wet cutting with cutting fluid.
5. Alumina-nitride cermet: The basic properties and processing range of this ceramic tool material are comparable to those of Al2O3-carbide cermet material, but it has better thermal shock resistance due to the substitution of carbide for nitride. And more suitable for new cutting. However, its flexural strength and hardness are lower than those of TiC-added cermets, and its research and in-depth development are still continuing.
6. Boron Nitride Ceramic Cutter: Recently, Sumitomo Electric Co., Ltd. developed a ceramic tool material with higher hardness—adhesive cubic boron nitride ceramic (CBN) sintered body. The sintered material is prepared by sintering at a pressure of 7 to 80 Pa at an ultrahigh temperature and high pressure of 2,300 to 2,400 ° C for 10 minutes. This technology also includes unique software technologies such as grinding fine powder diameters to improve CBN purity during the raw material preparation stage. A sintered boron nitride ceramic material having a CBN content of 100% is developed by combining fine particles having a particle diameter of 0.5 mm or less.
Ceramic tools made of boron nitride material do not suffer from common thermal cracking and chipping at the tip end of the tool when cutting hard steel with very high hardness. According to different conditions, the use time of boron nitride ceramic tools can be extended by more than 10 times compared with CBN sintered bodies containing other bonding materials, and it can be used as a material for interrupted cutting. Especially in the automotive industry, hBN sintered bodies are widely used in machining as cutting materials for machining hard cast iron materials such as engines.
Since the prior sintered body contains a particulate binder, it cannot form a unique property such as hardness and thermal conductivity as high as CBN. For example, CBN direct conversion technology is not suitable for high-speed cutting tools because its granularity is too coarse.
7, silicon nitride ceramic tools: silicon nitride ceramic tools have low density, high strength, high hardness physical properties. Its room temperature hardness value has exceeded the hardness of the best cemented carbide tool, which greatly improves its cutting ability and wear resistance, and can process all kinds of hard steel and hardened cast iron with high hardness. Its flexural strength has exceeded that of high-speed and is comparable to ordinary cemented carbide. The fracture toughness value of silicon nitride ceramic tools is 6~7mpaVm better than other series of tools. The thermal resistance index of silicon nitride ceramic tools is as high as 600-800 °C, which is obviously superior to other series of ceramic tools (300-400 °C), and its cutting speed is also 3 to 10 times higher than that of cemented carbide tools. Therefore, in the processing of high-strength intermittent parts, it shows its superior performance.
Silicon nitride ceramic tools include: pure silicon nitride ceramic tools and silicon nitride composite ceramic tools.
1 pure silicon nitride ceramic cutter, its hardness HRA91～92, bending strength 700～900Mpa, fracture toughness 4.2～5.2MpaVm, heat resistance up to 1300～1400°C, its thermal expansion coefficient is 3.0×10-6/°C, Has good antioxidant properties. 2 silicon nitride composite ceramic cutter; it is a ceramic tool made by adding a composition of Al2O3, Y2O3, TiC, TiN and MgO to a silicon nitride matrix, and using a composite strengthening effect and cold pressing sintering, the performance of which is superior to that of hot pressing. Pure silicon nitride ceramic tool.
For example, the addition of Al2O3 sintered ceramic tools to silicon nitride, combined with the characteristics of Al2O3 and SiN4, is higher than that of hard alloy tools and alumina ceramic tools, and the cutting edge temperature is higher than 1000 °C. Its biggest advantage is to increase the cutting speed, increase the feed rate, increase the metal removal rate and extend the tool life. Silicon nitride ceramic tools are particularly suitable for cutting a variety of cast irons and superalloys, but can not process steels that produce long chips.
All in all, with the deepening of the research and development of special ceramic materials, the proportion of ceramic tools in the metal cutting and processing industry has been expanding. With the development requirements of the aerospace and aerospace industries, it is necessary to meet the requirements for improving the cutting efficiency of workpiece materials such as Ti alloys and Ni-based superalloys, and special ceramic tool materials will make greater contributions.
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