Preparation method of polycrystalline cubic boron nitride (PcBN) composite material

Abstract

The invention relates to a preparation method of a polycrystalline cubic boron nitride (PcBN) composite material, which comprises the following steps: by using nonstoichiometric titanium nitride (TiNX, 0.3<=x<=0.6) as the basic component of a binder in the PcBN composite material, constituting a binder with one or both of aluminum nitride (AlN) and titanium carbide (TiC), and sintering with monocrystalline cubic boron nitride (cBN) under the conditions of high temperature and high pressure to prepare the PcBN composite material, wherein the pressure is 4-6.5GPa, the temperature is 1400-1650 DEG C, and such pressure and temperature are kept for 1-25 minutes. Since the PcBN composite material is prepared from the cBN and the binder mainly composed of the nonstoichiometric titanium nitride (TiNX, 0.3<=x<=0.6), the polycrystal does not contain any simple substance element or alloy phase, thereby avoiding the existence of soft spot. The hardness of the obtained PcBN composite material is up to 38-55GPa, and the fracture toughness is up to 3.31-4.12MPa.m1/2.

Description

technical field [0001] The invention belongs to the field of composite materials and relates to a method for preparing cubic boron nitride polycrystalline (PcBN) composite materials. Background technique [0002] PcBN (Polycrystalline CubicBoron Nitride, Polycrystalline CubicBoron Nitride) is prepared by bonding tiny single crystal particles of cubic boron nitride (cBN) under high temperature and high pressure (1350~1650℃, 4~6.5GPa) with a binder. PcBN (hereinafter referred to as PcBN) is used to make tool materials for processing hardened steel, chilled cast iron, ultra-high-strength iron group alloys, titanium alloys and other difficult-to-machine metals. The binder that plays a bonding role accounts for 5-40% of the mass ratio, which will seriously affect the overall performance of PcBN. The most important indicator of tool material is hardness. The ideal PcBN is that there is no binder or the hardness of the binder is as close as possible to cBN. [0003] Based on the ...

AI Technical Summary

Problems solved by technology

However, the obvious defect is that the residue of single element metal or alloy will reduce the high strength, hardness and heat resistance of PcBN, and the residue is unavoidable

The same is true for Chinese patent [2] (Chen Qiang, Zhang Cunsheng, Lin Shuzhong, a powder binder for cubic boron nitride composite sheet, CN102011040A, 2011.4.13). Although the addition of Co improves the toughness, the residue decreases The hardness and heat resistance of the sintered body are improved; Chinese patent [3] (A.R. Tversky, N. Kan, cubic boron nitride compact, CN101627139A, 2010.1.13) adopts metal-based bonding in order to improve toughness Although the heat resistance of the metal used is better, the maximum operating temperature is below 1100°C; Chinese patent [4] (Takaoka Hidemitsu, Tajima Yiro, surface-coated cubic boron nitride-based ultra-high pressure sintering The cutting tool made, CN101077645A, 2007.11.28), through the surface coating of cubic boron nitride to obtain the surface multilayer structure and improve the sintering ability, but the process is troublesome, and the elemental elements remain, and the use temperature is also reduced

Chinese patent [5] (Abs-Sami. Malik, Stephen Dole, Cubic Boron Nitride Ceramic Composite Material and Its Preparation Method, CN1022116007A, 2011.11.12) and considerations of the present invention in terms of heat resistance and toughness Basically the same, but aluminum nitride, silicon nitride and carbide are used. For the problem of difficult sintering, lanthanide oxides and even aluminum are added. Whiskers (silicon nitride, silicon carbide crystals) are added to increase toughness. beard), to a certain extent, it increases the difficulty of mixing uniformity, and there are certain problems