Cubic boron nitride Overview

CBN is a hexagonal lattice of boron nitride (H-BN) under heat and pressure, the activator effect polymerization conversion into high-density cubic lattice (C-BN)

single crystal, the crystal type structure similar to diamond, its hardness only to diamond of 7000 ~ 9000HV, the boron and nitrogen atoms, and its chemical and

thermal stability than carbon atoms in diamond. Widely used for machining hardened steel, chilled cast iron, heat-resistant alloys and other ferrous metals.
Brief introduction
cubic boron nitride single crystal particles is very small, only can be used for abrasives. In order to make the tool, it needs to be further various combinations with

or without agent (phase) and then sintered at high temperature high-pressure polymerization of PCBN PCBN isotropic polycrystalline block. It is made with high speed

and efficiency to meet a variety of processing requirements, the overall composite as a whole or with carbide blade (PCBN time usually about 0.5mm thick), then it is

welded or mechanical clamping into various Use of the tool, which known CBN cutting tools.
Feature
Cubic boron nitride (CBN) in hardness only to diamond. And the diamond is different, it is in the processing of ferrous metals chemical reaction hardly occurs. Through

a high-temperature high-pressure technology, people can carbide layer is bonded tightly homogeneous poly crystal cubic boron nitride coating. This poly-crystalline

cubic boron nitride referred PKB. BZN * - blades can replace conventional grinding process for hardening steel material treated (HRC45-68) also enables high-speed

finishing, cutting speed can reach 80-200m/min. BZN * - pearlitic cast iron blade is also used for cutting and hard cast iron and alloy cast iron.
Method
A single crystal cubic boron nitride sintered body and polycrystalline two kinds.
Single crystal is hexagonal boron nitride and the catalyst at a pressure of 3000 to 8000 MPa, the temperature is within the range 800 ~ 1900 ℃ system. Typical

catalyst materials selected from alkali metals, alkaline earth metals, tin, lead, antimony and their nitrides. Cubic boron nitride crystal with tetrahedral truncated

cone, octahedron, distorted crystal and double crystal, etc.). Industrial production CBN black, amber and surface metallization, the particle size is usually below 1

mm. It has superior thermal stability of diamond and iron group metals chemically inert, for the manufacture of abrasive, suitable for processing both hard and tough

materials such as high-speed steel, tool steel, tool steel, bearing steel, nickel and cobalt-based alloy, chilled cast iron. CBN abrasive grinding with steel, the most

grinding ratio and obtain high surface quality.
Polycrystalline cubic boron nitride sintered body of the main system of law are: ① a cubic boron nitride powder and a small amount of binding agent (such as cobalt,

aluminum, titanium, titanium nitride, etc.) at a pressure of 4000 to 8000 MPa, a temperature of 1300 ~ 1900 ℃ sintered under; ② to cubic boron nitride powder and a

binding agent layer to carbide (sheet or powder) as a layer, the above pressure and temperature, the two sintered together to obtain a cemented carbide substrate with

a polycrystalline sintered body, this sintered body has high strength, while maintaining the original physical and chemical properties of cubic boron nitride, can be

made up to 16 mm in diameter of the wafer, after cutting into a suitable shape as turning and boring knife blade, suitable for cutting hardened steel, cast iron and

nickel-based alloys.
Application
CBN grinding tools and tool mainly used for the production, that is used for grinding and cutting. CBN abrasives and abrasive products (corundum, silicon carbide

abrasive), compared with grinding sharp, good wear resistance, high processing efficiency (ease of automation), excellent surface quality (inside surface compressive

stress), high precision, long life, low unit processing cost, energy-saving and environmental improvement, etc., so it is widely used in automobiles, tractors,

bearings, machine tools, gear, tools, abrasives, aerospace, military and many other industries, particularly for high-speed steel, heat-resistant steel, stainless

steel, heat-sensitive materials, high hardness, toughness, high temperature strength, low thermal conductivity materials, precision grinding.
Ceramic CBN grinding not only has sharp cutting, cutting force is small, high efficiency, long life, easy shaping and sharpening, grinding, high precision, but also

has grinding workpiece temperature is low, the surface can eliminate residual tensile stress stress, so that the workpiece durability increased by 30% -50% of the

characteristics, therefore, vitrified CBN grinding to get the sudden emergence in recent years of development.