Cubic boron nitride
Cubic boron nitride
Cubic boron nitride (CBN) is a new synthetic material developed in the 1950s.
|中文名||立方氮化硼||Special point||High hardness|
|English name||Cubic boron nitride||Use||Cutting tool material|
There are two kinds of cubic boron nitride: single crystal and polycrystalline sintered body. Single crystal is prepared by boron hexagon nitride and catalyst in the range of pressure of 3000 ~ 8000 mpa and temperature of 800 ~ 1900℃. Typical catalyst materials are selected from alkali metals, alkaline earth metals, tin, lead, antimony and their nitride compounds. The crystal forms of cubic boron nitride include truncated cone of tetrahedron, octahedron, skew crystal and twin crystal. Industrial cubic boron nitride is available in black, amber and metallized form, usually with particle sizes below 1 mm. It has better thermal stability than diamond and chemical inertness to iron group metal, so it is suitable for grinding hard and tough materials, such as high speed steel, tool steel, die steel, bearing steel, nickel and cobalt-based alloy, chilled cast iron, etc. High grinding ratio and machining surface quality can be obtained by using cubic boron nitride grinding tools to grind steel.
The main methods of preparing cubic boron nitride polycrystalline sintered body are as follows: (1) using cubic boron nitride powder and a small number of binder (such as cobalt, aluminum, titanium and titanium nitride), sintering at pressure of 4000 ~ 8000 mpa, temperature of 1300 ~ 1900℃; (2) with cubic boron nitride powder and binder as a layer, cemented carbide (or powder) as a layer, under the pressure, temperature, put the two sintering together, made with cemented carbide substrate polycrystalline sintered body, this kind of sinter with high intensity, while maintaining the original physical and chemical properties of cubic boron nitride, can be made into 16 mm in diameter wafer, cutting into the appropriate shape, as a tool and boring cutter head, suitable for cutting hardened steel, cast iron and nickel alloy, etc
Range of application
Cubic boron nitride abrasive grinding performance is very good, not only qualified for grinding hard materials processing, improve productivity, and to strictly control the shape and size precision of the workpiece, also can effectively improve the quality of grinding workpiece, improve workpiece surface integrity after grinding, thus increasing the fatigue strength of the parts, prolong the service life, increased reliability, coupled with cubic boron nitride abrasive production process in terms of energy consumption and environmental pollution than ordinary abrasive production as well, therefore, to expand production and application of cubic boron nitride grinding tool is mechanical application is inevitable trend in the development of mechanical industry.
1, Tungsten, tungsten molybdenum and other high-speed steel, especially vanadium alloy steel, cobalt alloy steel, special high-speed steel tool grinding and rough grinding.
2. Fine grinding and final grinding of precision parts made of heat-resistant steel, stainless steel and high-hardness alloy structural steel. When these parts are used with ordinary abrasive tools, high precision cannot be obtained because the abrasive tools are consumed or blunt too quickly.
3, The local thermal stress and thermal shock sensitive to the grinding of various materials.
4, Large precision workpiece (machine guide rail, high precision machine screw) fine grinding and final grinding. The high grinding temperature often leads to large thermal deformation of these workpieces, so high precision can not be obtained.
5. Fine and final grinding of work pieces (instruments and parts for miniature bearings) that are mass-produced on automatic and semi-automatic machine tools.
6, The grinding of workpiece (gear shaper, broach, high-precision gear, mold, punch) with complex surface with good angular maintenance is required.
7. Surface grinding of thread tool and thread gauge (tap, thread roller, thread plug gauge, etc.).
8, Refractory heat resistant steel workpiece ultra-finishing.
9. Grinding other steel quenching tools