【作者】 熊继；

【导师】 沈保罗；

【作者基本信息】 四川大学 ， 材料学， 2003， 博士

【摘要】 由于Ti（C，N）金属陶瓷具有更高的热硬度、更好的抗氧化性和抗高温蠕变能力，因此被广泛用做刀具材料。Ti（C，N）金属陶瓷刀具材料的主要原料是钛，钛在地球上的贮量为传统的WC基硬质合金刀具材料的主要原料W的70倍，具有极大的成本和资源优势。因此，Ti（C，N）金属陶瓷成为近期各国研究的主要刀具新材料之一。 基于超细WC基硬质合金的使用现状及Ti（C，N）基金属陶瓷刀具材料的发展概况、研究进展，本文采用X射线衍射仪（XRD）、扫描电镜（SEM）、透射电镜（TEM）、电子探针（EPMA）、热等静压烧结炉（HIP）、低压烧结炉（SH）等对高性能超细Ti（C，N）金属陶瓷刀具材料进行了系统研究。 首先针对国内外在研究细颗粒Ti（C，N）金属陶瓷遇到的原料氧含量高，难以获得优质细颗粒Ti（C，N）金属陶瓷的现状，分析了超细原料中氧含量高的原因。用市购平均粒度0.13μm的TiC_0.7N_0.3粉末，通过H₂还原炉处理或真空炉处理，获得了平均粒度小于0.2μm、氧含量低于0.3wt％的优质超细TiC_0.7N_0.3原料。 在普通金属陶瓷的工艺的基础上，进一步研究了Mo₂C、WC、TaC等添加成分对TiC_0.7N_0.3超细合金性能的影响。 针对超细原料比表面积大、活性高、易于团聚等特点，优化了制备超细金属陶瓷混合料的球磨工艺参数；采用合适的分散剂改善料浆的粘滞性，使超细颗粒表面为活性分子层包围，获得好的研磨效果。研究表明，超细金属陶瓷在900℃以下的低温状态发生了较普通金属陶瓷激烈得多的固相扩散反应，这是使超细金属陶瓷芯、环结构变得复杂的原因之一；在900℃-1230℃之间的反应较平缓，但从晶格常数的变化看，其反应的程度却比普通金属陶瓷的高；在1230℃以后，反应又开始激烈，并出现了脱氮反应。与不加粘结相的超细混合料的对比研究发现，在较高温度时粘结相对物相的演变起了重要作用，这些研 四川大学博士学位论文究结果为制定有效的烧结工艺提供了依据。根据超细金属陶瓷物相的演变规律，修改了常规烧结普通金属陶瓷的工艺路线。由于超细金属陶瓷液相的提前出现，必须在较低的温度下延长烧结时间以脱除有害的吸附物和低熔点挥发物。在未发生脱氮反应之前，采取充氮气的办法进行烧结。由于金属陶瓷中液相的流动变得困难，必须采取加压烧结，以消除孔隙，提高超细金属陶瓷的性能。 对超细金属陶瓷的断口进行了分析。统计分析表明，超细金属陶瓷的断裂源主要为孔隙，同时还有少量的Ni池等。应用铃木寿的强度理论，计算出超细金属陶瓷的本征强度为5000 MPa，比实测值高得多。分析表明，主要是孔隙等缺陷造成了强度下降，并指出，降低孔隙、Ni池等缺陷将有利于金属陶瓷强度的提高。 田宫夺拱玄撬射由倍夺索斤了韶加全屋胸咨知酋宁甭今屋脚咨的黝又甲如玄9姑 川」l石」7J刀士匕午三J乙之力，J.七芍毛/J叼1 JJ七旦牛田j」乙，丙卜叼心乙布目曰声刀又习乙，丙卜叼仁七口，J’p吠乃训3类上1匀、多口构。两种金属陶瓷的组成相是一样的，主要由（Ti，Mo，Ta，w）（C，N）固溶体和Co（Ni）固溶体构成，（Ti，Mo，Ta，W）（C，N）固溶体是硬质相，Co（Ni）固溶体是粘结相。C。（Ni）粘结相中有纳米硬质相析出。超细金属陶瓷的硬质相中有位错也有孪晶， 最后，将制得的超细金属陶瓷刀具同市售的普通金属陶瓷、日本超细金属陶瓷及WC基硬质合金P10作了对比切削试验。结果表明，超细NT6B金属陶瓷的切削寿命最长，其寿命超过了日本NX2525，是普通市售金属陶瓷寿命和WC基硬质合的2一3倍。刀具的切削力最小，被加工材料的表面光洁度最高。更多还原

【Abstract】 Ti(C,N)-based cermets have been widely used as the tool materials because of its higher red hardness, better resistance to oxidation, and better resistance to creep at high temperature. The key alloying element used in Ti(C,N)-based cermets tool materials is titanium that has about 70 times storage in the earth than tungsten, hence Ti(C,N)-based cermets show great advantage in cost and resources more than that of the traditional WC-based cemented carbide and become one of the new and main tool materials which have being developed in the globe.Based on a review of the ultra-fine WC-based cemented carbide being used in cutting tool materials, and development and progress of Ti(C,N)-based cermets tool materials, a high-performance ultra-fine Ti(C,N)-based cemented carbide has been studied systematically in this dissertation using all kinds of apparatus such as X-ray diffractometer (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), electron probe (EPMA), hot isostatic press machine (HIP), low-pressure sintering machine (SH), etc.At first, the reason why oxygen content is high in raw material has been deeply analyzed in order to surmount the crux that high-performance cermets containing ultra-fine particles Ti(C,N) is hard to obtain due to the high content of oxygen in raw materials, then a high-performance raw Ti(C,N) powder which average size of particle TiC0.7N0.3 is less than 0.2μm and oxygen content is lower than 0.3wt% has been prepared adopting the conventional TiC0.7No.3 powder which average size is 0.13μm by means of a treatment in vacuum furnace or in hydrogen-deoxidization furnace.On the basis of common production process of cermet, the effect of addition such as Mo2C, WC, TaC on the properties of the ultra-fine cermet has been further investigated.Considering that the ultra-fine particle features high specific surface, high activity, and being easy to pileup, the technology of wet ball milling for the ultra-fine powder has been optimized and a certain dispersant is adopted to improve the stickiness of the slurry so that the ultra-fine grains can be covered by a layer of active material, thus leading to excellent milling behavior. The results investigated indicate that the ultra-fine cermet would have much more ability to occur solid diffusion reaction than common cermet at the lower temperature of 900癈. It is one of the reasons that makes the core-rim structure of ultra-fine become rather complicated. It seems that the reaction became milder at 900~1230癈, but the degree of reaction should be higher than the common cermet according to the changes of the lattice parameter. However, the reaction would become intense again at the temperature above 1230癈, and it could be deduced that the reaction between liquid phases occurs in advance while the denitrogenization reaction appears. Compared with the result obtained in the ultra-fine powder without binder-phase, it is shown that the binder-phase definitely has very important role in the evolvement of phases, and the phase evolvement provides a basis for optimization of technology. Based on the evolvement rule for the phases in the ultra-fine cermet, the conventional sintering technology for the common cermet has been optimized. As the liquid phase appears in advance, the sintering time has to be kept longer to remove the harmful adhesive and volatile, which have lower melt point. Certain N2 gas has to be supplemented in the sintering process to avoid appearance of the denitrogenization reaction. As it is difficult for the liquid phase to flow in the ultra-fine cermet, pressure sintering is used to eliminate the porosity to upgrade the properties of ultra-fine cermet.The fracture of the ultra-fine cermet has been analyzed systematically. The results show that rupture usually occurs can be attributed to the porosities or some very small Ni-lakes. Using Mr. Hisashi Suzuki’s strength theory, the essential strength of ultra-fine cermet is calculated to be 5000 MPa much higher than theIVtesting data, the rea更多还原