【作者】 项东；

【导师】 李木森；

【作者基本信息】 山东大学 ， 材料学， 2006， 硕士

【摘要】 本文针对金刚石因表面能较高，在刀具热压成型时难以与金属基体结合牢固，导致刀具受到较高的切削载荷时，金刚石易于脱落，使刀具寿命明显降低的现实问题，采用化学镀及其复合镀、盐浴镀等镀覆技术，在金刚石表面得到表面致密、结合较好、有一定厚度的化学镀层，以提高与金属基体的结合强度，改善刀具的表面质量，延长其使用寿命。通过试验研究，选择了适宜的化学镀预处理工艺，确定了化学镀Ni-W-P的最佳配方和工艺参数。采用体视显微镜、扫描电子显微镜、电子探针、X射线衍射仪等先进检测方法，对镀覆后及热处理后金刚石表面的镀覆层进行了微观组织、相结构和成分分析，找出了金刚石表面镀覆层的组织结构和性能之间的对应关系。对金刚石经过表面化学镀覆Ni-W-P后，再镀覆Ni-Ti-RE的复合镀覆方法所获得的复合镀层的微观结构、表面形貌、成分分布、相结构、相关性能和形成机理也进行了研究。采用适当的配方进行了金刚石表面盐浴镀铬和镀钛，对所形成的镀铬和镀钛层也进行了相关组织、结构和性能的研究。对上述各种镀覆和处理方法对金刚石表面形成镀覆层的反应机理进行了初步探讨。 结果表明，经化学镀、化学镀+复合镀后，金刚石表面能形成较致密的镀覆层，组织较均匀，与金刚石的结合较紧密，成分分布较合理，抗压强度提高，最大幅度可达到38.51％。金刚石表面形成的镀覆层经适宜的热处理后脱落较少。对金刚石表面形成镀覆层后再经过850℃热处理的样品进行XRD检测，证明金刚石表面与镀层之间已形成WC、TiC等碳化物。但此时金刚石镀层因氧化较严重，其抗压强度要比未镀覆合金层的低。金刚石进行化学镀及其复合镀后，表面有一层保护层，隔绝了金刚石与氧的直接接触，可以阻止金刚石的高温氧化。在经受高温热处理后，金刚石表面会产生很少量的脱落块，但表面形貌并没有明显的变化，表面镀覆层仍然保持完好。经过盐浴镀后，在金刚石表面也会形成有效的合金镀覆层。更多还原

【Abstract】 Due to the higher surface energy a diamond is hard to combine with the metal matrix of the cutting tool that is molded by hot-press. So the diamonds are easy to fall off when the cutting tool is under higher cutting loads, which leades to decrease the service life of the cutting tool. In order to deal with the above problem the technologies of chemical plating, chemical plating + duplex plating and salt-bath plating are adopted in this experiment. For increasing combining strength, improving the surface qualities of the cutting tool and prolonging their service life, the finer structure, better combining strength and definite thickness of plating layers on the diamond surface are obtained. A suitable pretreatment technics before the plating of diamond is found by the experiments. The best prescriptions and technical parameter of plating Ni-W-P are also confirmed. The advanced testing methods such as stereoscope, scanning electron microscopy (SEM) , electron probe microanalyzer (EPMA) , X-ray diffraction (XRD) and so on are adopted to analyze the microstructure, phase structures and ingredient of the surface layer of diamond after plating and heat treatment and find the dependences of the structures and performances out. At the same time, the forming process and mechanism, microstructure, surface appearance, composition distribution, phase structure and related performances of the duplex plating layers which form after plating Ni-W-P and duplex plating Ni-Ti-Re are studied. Otherwise, the Cr and Ti plating layers on diamonds are plated by suitable prescription. The related structure and performance of these plating layers are also studied. In this process, the reaction mechanisms of the every plating layers are discussed.The results show that the finer plating layers and well-distributed structure on the diamond surface are formed after the plating or the plating + duplex plating. These plating layers combine closely with diamond and their composition distribute更多还原