共价键化合物陶瓷结合剂对干切削PcBN刀具复合材料的影响

The Influence of Covalent Compound Ceramic Bond on Composite Materials of PcBN Cutting Tools for Dry Cutting

针对传统PcBN刀具材料由于结合剂的原因,存在整体热稳定性、抗磨损性偏低等问题,文章采用非化学计量比TiN_(0.3)、TiN_(0.3)+AlN及cBN表面镀钛等方法,研究了这些方法对结合剂与cBN界面结合的影响,讨论了界面形成的物相对PcBN性能的影响;文中采用SEM对样品的抛光表面和断口进行观察,利用EDS分析界面处的元素分布,利用XRD分析了样品的相组成;采用阿基米德排水法测量样品的密度,维氏硬度计测量样品的维氏硬度。利用高精密数控车床对PcBN刀具的切削性能进行了测试。结果证明:TiN_(0.3)与cBN复合后的界面通过中间相TiB_2相结合,AlN的加入促进了TiB_2的生成,并改善了TiN_(0.3)与cBN热膨胀系数的失配。cBN表面镀Ti后实现了界面成分的过渡,加入AlN后界面出现了Al元素的聚集。采用TiN_(0.3)作为结合剂主相,在结合相中添加其它强共价键类金属碳化物或氮化物,通过对原料成分与合成条件的控制,烧结后获得了无低熔点或低硬度相致密的PcBN烧结体。PcBN烧结体具有高硬度,高强度,优异的耐高温性和耐磨损性。通过以TiN_(0.3)作为结合剂主相与cBN的结合,成功制备了系列PcBN刀具材料,均被用来对淬火钢等硬质钢进行高速、高精度和高效切削,使以往主要采用磨削加工的难加工材料实现了切削加工。

As a result of the bonding agent, the raditional PcBN tool material has defects such as low overall thermal stability and low abrasion resistance. In view of these problems, the influence of some methods such as nonstoichiometry TiN0.3, TIN0.3 ＋ AlN and cBN surface titanizing on the bonding between bonding agent and cBN interface has been studied, and the influence of the phase formed on the interface on PcBN performance has been discussed; In this paper, the polished surface and fracture surface of the samples were observed by SEM, the element distribution at the interface was analyzed by EDS, and the phase composition of the sample was analyzed by XRD; the density of samples was measured by Archimedes drainage method, and the Vickers hardness was measured by Vickers hardness tester. The cutting performance of PcBN cutter was tested by high precision digital controlled lathe. Result shows that the interface of TiN0.3 and cBN is combined by intermediate phase TiB2, and AlN promotes the generation of TiB2 and improves the mismatch of thermal expansion coefficient between TIN0.3 and cBN. Transition of interracial components has been realized after cBN surface titanizing, and aggregation of Al elements on interface can be found when AlN has been introduced in. PcBN sintered compact without low melting point or low hardness has been prepared after sintering, using TIN0.3 as the principal phase of the binding agent. Duing the process, strong covalent bond metal carbides or nitride were added into the binding phase and the raw material composition and synthesis conditions were strictly controled. PcBN sintered compact has the characteristics of high hardness, high strength, excellent high temperature resistance and wear resistance. Series of PcBN cutting tool materials have been successfully prepared through the combination with cBN, using TIN0.3 as the principal phase of the binding a- gent. These materials are all used for the high speed, high precision and high efficiency cutting of hard steel such as chilled steel. Cutting of difficult-to-machine material which used to be machined through grinding method has been realized.