铁族金属对人造金刚石单晶腐蚀的研究

发布时间：2018-03-23 07:38

  本文选题：铁族金属　切入点：金刚石单晶　出处：《湖南大学》2015年硕士论文　论文类型：学位论文

【摘要】：金刚石因具有高硬度、高强度、高耐磨性以及高导热性等一系列优点而在许多领域得到广泛应用。但以共价键结合的金刚石具有较高的表面能,且人造金刚石单晶表面非常光滑,导致其在磨具中与结合剂之间的结合力较弱,缩短磨具的使用寿命。本文首次采用铁族金属高温催化腐蚀法对金刚石单晶进行表面处理,在金刚石表面形成腐蚀凹坑,增加金刚石的表面粗糙度,从而提高磨具中结合剂对其的把持力。论文主要研究内容及成果如下:1、分别以Fe、Co、Ni作为催化腐蚀剂,研究不同处理温度和保温时间对金刚石单晶表面腐蚀的微观形貌和腐蚀深度的影响。结果表明:在铁族金属的催化作用下,金刚石表面的腐蚀深度随着温度的升高、保温时间的延长而增加,与延长保温时间相比,升高处理温度对促进金刚石的腐蚀更有效。2、在相同腐蚀工艺条件下,金刚石的{100}面均比{111}面更容易被腐蚀,在{100}面倾向于形成倒立的金字塔状腐蚀坑,而在{111}面易于形成底部平坦光滑、外部轮廓为三角形或六边形的腐蚀坑,且腐蚀后金刚石单晶整体还保留了原来的颗粒形貌;拉曼光谱的分析结果表明,腐蚀坑的形成是金刚石的石墨化所致。3、腐蚀后金刚石的基本结构得到了保留,其强度随着处理温度的升高而略有降低。与未处理的金刚石单晶相比,960℃时,经Fe催化腐蚀后金刚石的TI值和TTI值分别降低3.17%和1.88%;930℃时,经Co催化腐蚀后金刚石的TI值和TTI值分别降低3.96%和2.18%,单颗粒抗压强度仅下降了5.6%。4、在实验条件下,采用Co腐蚀金刚石所需的处理温度最低,采用Fe腐蚀所需的温度最高;在870℃条件下,经Fe处理后的金刚石{100}面和{111}面的腐蚀率分别为0.939%、0.785%,在810℃条件下,经Co和Ni处理后的金刚石{100}面的腐蚀率分别为51.631%和13.278%,{111}面的腐蚀率分别为34.062%和4.158%,结合不同条件下金刚石表面腐蚀坑的分布情况表明:相对整颗金刚石而言,经Co处理后金刚石的表面腐蚀率最高且腐蚀均匀性最好,Ni次之,Fe最差。5、铁族金属催化腐蚀金刚石单晶的机理为:随温度的升高和保温时间的延长,固态金属逐渐熔融形成液相,使金属与金刚石之间的界面接触状态由点接触逐渐转变成面接触,熔融的金属促使碳原子由金刚石相转变为石墨相,并且形成的石墨相碳通过熔融金属向远离金刚石—金属界面的一端进行扩散。
[Abstract]:Diamond is widely used in many fields because of its advantages of high hardness, high strength, high wear resistance and high thermal conductivity. Moreover, the surface of synthetic diamond single crystal is very smooth, which leads to the weak bonding force between diamond and binder and shortens the service life of abrasive tool. In this paper, the surface of diamond single crystal is treated by high temperature catalytic corrosion method of iron group metal for the first time. Corrosion pits are formed on the surface of diamond to increase the surface roughness of diamond, so as to improve the holding power of binders in abrasive tools. The main contents and results of this paper are as follows: 1. The effects of different treatment temperature and holding time on the microstructure and corrosion depth of diamond single crystal surface were studied. The results show that the corrosion depth of diamond surface increases with the increase of temperature under the catalysis of iron group metal. Compared with prolonging holding time, increasing treatment temperature is more effective in promoting diamond corrosion. Under the same corrosion conditions, the {100} surface of diamond is more easily corroded than that of {111} surface. On the {100} plane, the inverted pyramidal corrosion pits tend to be formed, while on the {111} plane, the corrosion pits with flat bottom and smooth bottom and triangular or hexagonal exterior contour are easily formed, and the original morphology of the diamond single crystal remains after corrosion. The results of Raman spectra show that the formation of corrosion pits is caused by graphitization of diamond. The basic structure of etched diamond is preserved. Compared with the untreated diamond crystal at 960 鈩，

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