金刚石表面镀层在磨具中的作用机理

采用湿法镀（化学镀、电镀）或真空镀（蒸发镀、溅射镀、离子镀）方法,在金刚石表面镀覆一层铜、镍、钛、钼、钨等金属,或者它们的复合镀层。表面镀覆已经与单晶合成、分选、聚晶烧结、气相沉积一起,成为金刚石多品种专用化发展的五条重要途径之一。镀层赋予金刚石所需要的各种特有的物理化学性能,不仅可以提高金刚石颗粒强度以及与结合剂的结合强度,还有对金刚石表面的宏观隔离保护作用和对金刚石结构的微观侧面支撑作用．从而有利于防止金刚石在使用过程中被氧化和石墨化。特别是在树脂结合剂磨具中,镀层的热导率介于金刚石和树脂之间,可以有效地减缓磨削热脉冲对树脂造成的热损伤,从而显著延长其耐用度,使树脂磨具的使用寿命提高50％-100％。     

金刚石微粉表面镀覆对线锯的关键作用分析

在分析电镀金刚石线锯工艺流程的基础上,指出了金刚石上砂是电镀线锯最关键的工艺环节.探讨了各种上砂方法及特点,分析了镀覆金刚石微粉对上砂的作用.指出,采用与金刚石形成化合物结合的镀覆金刚石,如镀钛、镀钨、镀钼、镀铬和复合镀的金刚石,有利于高质量金刚石线锯的生产;避免了采用单一镍镀层产生“双极性”效应,导致镍涂层脱落的问题;具有上砂速度快,上砂容易的特点;镍镀层对镀覆金刚石颗粒迅速整体覆盖,镍镀层生长迅速,与镀覆金刚石结合牢固,出刃高;解决了无镀层金刚石以及单一镀镍金刚石与基体结合力差的问题.因此,镀覆金刚石为生产高质量金刚石线锯提供了有力的技术支持.     

金刚石表面复合镀层结构及可钎焊性研究

本通过对金刚石表面镀覆Ti及Ti Ni等不同镀层研究，研究了不同镀层条件下金刚石可钎焊能力，利用XRD，EDS等研究了金刚石与镀层，镀层与焊料之间的结合关系，研究表明，表面具有金属性质的镀覆Ti Ni镀层的金刚石可焊性大幅度提高，与焊料金属润湿良好，复合镀层的贡献显，这主要得益于Ti镀层与金刚石的冶金结合及Ni镀层更为优异的抗氧化能力，进而可改善金属结合剂金刚石工具的使用性能。     

复合镀钛——镍金刚石的钎焊

本论介绍了钎焊金刚石的一种新工艺。经真空微蒸发镀钛的金刚石颗粒,采用电镀方法下一步复合镀覆金属镍,在金刚石表面形成一种复合支。因为这种复合镀层与金刚石界面结合,采用高频感应加热的方法,选胜使用合适的钎料,在空气中可以顺利实现金刚石与金属基体的焊接。结果表明,钎料与金刚石之间完全润湿,金刚石与基体焊接牢固,利用钎焊导向棒测定其界面结合强度达到140MPa。     

超硬材料系列镀覆产品及应用

以真空微蒸发镀覆技术为核心，围绕各类高性能超硬材料工具的不断开发应用，目前已经形成了超硬磨料镀覆系列产品。包括镀覆一层金属的超硬磨料，如镀钛、镀钨的金刚石；镀覆合金的超硬磨料，如镀钛－铬合金的金刚石；真空微蒸发镀覆之后再经电镀形成的多层复合超硬磨料，如复合镀Ti-Ni的金刚石等。这些系列镀覆产品分别适用于金属粉末烧结工具、钎焊工个和树脂结合剂工具，以于提高工具质量、降低制造成本和新产品开发有显著作用。新近研制成功的一种适用于树脂结合剂工具的刚玉涂覆的超硬磨料，克服了镀镍、镀铜超硬磨料镀覆成本高及使工具变钝的缺点，是树脂工具升级换代的新产品。     

金刚石表面镀钛及其在胎体中结合状态的研究

采用真空蒸发-扩散镀的方法在金刚石表面镀钛,研究了镀覆温度和保温时间对金刚石表面形貌、镀层厚度、镀层物相的影响规律,分析了镀钛金刚石的抗氧化性能,研究了镀钛金刚石及其在铁基胎体中的结合状态。结果表明:在低温下（680℃）镀覆时,金刚石表面开始出现TiC;随镀覆温度升高或保温时间延长,镀层逐渐致密并增厚,在720℃镀覆时出现Ti沉积,在820℃镀覆时由于应力原因产生裂纹并导致镀层的破坏;镀层可隔绝金刚石与氧的直接接触,大幅度延缓氧对金刚石的侵蚀作用;镀钛后金刚石在胎体中可实现牢固的冶金键合。      

金刚石真空微蒸发镀钛的一些延伸产品及应用

以真空微蒸发镀覆技术为核心，围绕各类高性能超硬材料工具的不断开发应用，目前已经形成了超硬磨料镀覆金属化系列产品。包括镀覆单一金属的超硬磨料，如镀钛、镀钨的金刚石；镀覆合金的超硬磨料，如镀钛－铬合金的金刚石；真空微蒸发镀覆之后再经电镀形成的多层复合镀超硬磨料，如复合镀Ti-Ni具质量、降低制造成本和新产品开发有显作用。     

金刚石的真空微蒸发镀技术

超硬磨料真空微蒸发镀覆技术是燕山大学完成的国家重点科技攻关项目，是一项国内外首创，处于国际领先水平的成果。尽管各种镀覆技术很多，除真空微蒸发镀覆技术外，还没有其它方法能够用于生产实际中。技术领先的标志是，真空微蒸发镀钛金刚石受热温度低至650℃，可在650～750℃之间任选，镀层与金刚石界面形成碳化物达到强力结合，结合强度大于140MPa；镀后单晶强度提高5％～20％；镀后增重随粒度不同在0．5％～3．0％。在工具烧结时，微蒸发镀钛层保护金刚石，工具中金刚石颗粒不脱落，出刃增高，工具寿命和效率大幅度提高。适用于各类金属结合剂金刚石工具。减少金刚石用量，降低生产成本。     

镀钛超硬材料微粉及应用

本文报道了采用真空微蒸发镀覆技术进行工业化超硬材料微粉镀覆生产。镀覆钛和久合金的超硬材料（金刚石、立方氮化硼）微粉主要技术指标为;镀覆微粉的粒度最细达到５μ（Ｗ５）,镀后无颗粒粘连,镀层均匀并且与超硬颗凿强力冶金结合,镀层光亮闪烁金属光泽。镀覆钛和钛合金的超硬材料微粉在各类精细超硬工具制造和超硬超晶材料领域有广泛应用前景。     

金刚石粉体表面CVD法镀钨的工艺研究

目的增强金刚石与基体的界面结合能力。方法首先对金刚石粉体进行"除有机物→除油→粗化→烘干"处理。采用自制化学气相沉积装置,研究了以H_2和WF_6为反应气体在金刚石表面CVD法镀覆钨工艺。使用扫描电镜(SEM)、能谱(EDS)、X射线衍射(XRD)、透射电镜(SEM)等检测方法,分析了金刚石粉体镀层钨的微观形貌、成分、组织结构,对镀层包覆金刚石粉体相关性能进行了初步测试。结果在粒径约为223.6mm的金刚石表面获得均匀致密镀覆层的最佳工艺参数为:沉积温度670℃,沉积时间2 min,H_2通入量1 L/min,WF_6消耗量2 g/min。沉积温度为580℃时,获得的均匀致密钨镀层的厚度为150 nm,且镀层杂质含量较少。将镀覆钨的金刚石和普通金刚石分别与铜粉热压烧结后进行抗弯强度测试,结果显示含镀覆钨的金刚石试样抗弯强度提高了38.6%。加入镀钨金刚石压块的热膨胀系数比加入普通金刚石的有所降低,并且加入的镀钨金刚石粉体越多,压块的热膨胀系数越低。结论镀钨后的金刚石颗粒的表面性能得到改善,与基体的结合能力得到提高。     

Adhesion analysis and dry machining performance of CVD diamond coatings deposited on surface modified WC-Co turning inserts

This paper investigates the effects of different surface pretreatments on the adhesion and performance of CVD diamond coated WC-Co turning inserts for the dry machining of high silicon aluminum alloys. Different interfacial characteristics between the diamond coatings and the modified WC-Co substrate were obtained by the use of two different chemical etchings and a CrN/Cr interlayer, with the aim to produce an adherent diamond coating by increasing the interlocking effect of the diamond film, and halting the catalytic effect of the cobalt present on the cemented carbide tool. A systematic study is analyzed in terms of the initial cutting tool surface modifications, the deposition and characterization of microcrystalline diamond coatings deposited by HFCVD synthesis, the estimation of the resulting diamond adhesion by Rockwell indentations and Raman spectroscopy, and finally, the evaluation of the dry machining performance of the diamond coated tools on A390 aluminum alloys. The experiments show that chemical etching methods exceed the effect of the CrN/Cr interlayer in increasing the diamond coating adhesion under dry cutting operations. This work provided new insights about optimizing the surface characteristics of cemented carbides to produce adherent diamond coatings in the dry cutting manufacturing chain of high silicon aluminum alloys.     

影响CVD金刚石涂层工具界面结合强度的因素及改进措施

化学气相沉积法制备金刚石涂层硬质合金工具综合了金刚石与硬质合金的优异性能,广泛应用于切削难加工材料。金刚石与硬质合金基体界面结合强度是评价金刚石涂层的一个重要性能指标。本文主要介绍了影响CVD金刚石涂层工具界面结合强度的主要因素,并对如何提高其界面结合强度的方法进行了较深入的探讨,同时科学论述了金刚石涂层结构的优化设计理念,以解决金刚石涂层附着强度低、表面粗糙度高等关键技术,这对如何提高硬质合金基体与金刚石涂层之间的界面结合强度具有一定的实际指导意义。     

Microstructure and thermal expansion of Ti coated diamond/A1 composites

A titanium coating fabricated via vacuum vapor deposition for diamond/Al composites was used to improve the interfacial bonding strength between diamond particles and Al matrix, and the Ti coated diamond particles reinforced Al matrix composites were prepared by gas pressure infiltration for electronic packaging. The surface structure of the Ti coated diamond particles was investigated by XRD and SEM. The interfacial characteristics and fracture surfaces were observed by SEM and EDS. The coefficient of thermal expansion(CTE) of 50% (volume fraction) Ti coated diamond particles reinforced Al matrix composites was measured. The Ti coating on diamond before infiltration consists of inner TiC layer and outer TiO₂ layer, and the inner TiC layer is very stable and cannot be removed during infiltration process. Fractographs of the composites illustrate that aluminum matrix fracture is the dominant fracture mechanism, and the stepped breakage of a diamond particle indicates strong interfacial bonding between the Ti coated diamond particles and the Al matrix. The measured low CTEs (5.07×10⁻⁶−9.27×10⁻⁶K⁻¹) of the composites also show the strong interfacial bonding between the Ti coated diamond particles and the Al matrix.     

Interface fracture behavior of electroplated coating on metal substrate under compressive strain

The inducement of interface fracture is crucial to the analysis of interfacial adhesion between coating and substrate. For electroplated coating/metal substrate adhering materials with strong adhesion, interface cracking and coating spalling are difficult to be induced by conventional methods. In this paper an improved bending test named as T-bend test was conducted on a model coating system, i.e. electroplated chromium on a steel substrate. After the test, cross-sections of the coated materials were prepared to compare the failure behaviors under tensile strain and compressive strain induced by T-bend test. And the observation results show that coating cracking, interface cracking and partial spalling appear step by step. Based on experimental results, a new method may be proposed to rank the coated materials with strong interfacial adhesion.     

Analysis of tool wear and residual stress of CVD diamond coated cemented carbide tools in the machining of aluminium silicon alloys

Aluminium alloys have found increasing applications in the automotive and aeronautical industries in recent years. Due to their extraordinary properties however, the machining of these alloys still poses difficulties, and requires the optimized combination of cutting tool material and geometry. The potential of CVD diamond coated carbide tools has been demonstrated in recent years, however tool wear and short tool life remain as issues to be resolved. Key to increasing the tool life of CVD diamond coated tools is the further development of the coating process to optimize the coating adhesion. An understanding of the substrate and coating residual stress profiles must be gained in order to achieve this. Compressive residual stresses in cutting tools can lead to a higher crack resistance, but also to early coating delamination and tool failure. To analyze the influence of residual stresses on the coating quality and tool life, the residual stress profiles of tungsten carbide substrates and CVD diamond coatings were measured using X-ray and synchrotron radiation. The influence of the tungsten carbide substrate type and the CVD diamond coating process on the residual stress profiles was thus determined. In order to analyze the performance of the coated tools and the influence of the residual stresses on the tool lifetime, machining tests were performed with two aluminium silicon alloys. The tool wear, tool lifetime and workpiece quality were examined. Finally, many of the commonly used wear tests used to analyze the wear resistance of tool coatings cannot be implemented for CVD diamond coatings due to their high hardness. An impact test was therefore constructed to allow the determination of the wear resistance of CVD diamond tools.     

钛过渡层与硬质合金基体表面结合状况对金刚石薄膜附着力的影响

以WC-6％Co为基体,采用磁控溅射法,在原始试样、酸腐蚀试样以及酸蚀后进行氢等离子体脱碳处理的试样上制备Ti过渡层,然后碳化过渡层为TiC。在热丝化学气相沉积装置中,制备金刚石薄膜。研究三种不同试样上的金刚石薄膜与基体的附着力。结果表明,在原始试样上的金刚石薄膜在冷却过程中自动脱落;在经等离子体处理后的试样上,金刚石薄膜与基体间附着力高于在经酸蚀处理的试样上的金刚石薄膜与基体附着力。造成这种现象的主要原因可能是等离子体脱碳还原处理降低WC晶粒表面能,增强Ti与WC间的结合强度,导致TiC过渡层与WC基体结合强度增加,从而增加金刚石薄膜附着力。     

压痕法研究镶嵌结构界面金刚石膜粘附性能

在铜基体上沉积Cu(Cr)-diamond复合过渡层,用热丝CVD法在复合过渡层上沉积出金刚石膜。用压痕法对沉积的金刚石膜/基结合性能进行了研究。结果表明,在Cu-diamond上沉积的金刚石膜,用147 N压痕时压痕边缘出现大面积崩落,并在基体表面留下被拔出的金刚石凹坑;在Cu-diamond中掺入微量Cr,压痕边缘只形成环形裂纹,增大压痕载荷至441 N,环形裂纹区域增大,并出现部分崩落,崩落区域有被切断的金刚石残留。在Cu-diamond复合层中掺入微量Cr能显著提高金刚石膜/基结合力。     

金刚石涂层刀具加工石墨的切削性能

为充分对比不同类型金刚石涂层刀具的切削性能,定制几种不同类型金刚石涂层刀具进行等静压石墨切削加工,并与WC硬质合金刀具和TiAlN涂层刀具的切削情况对比,分析不同类型金刚石涂层刀具的涂层形貌、切削寿命、加工后的表面质量以及切削力。结果表明:制备的金刚石涂层刀具的涂层形貌主要为纳米晶和微晶,其寿命是硬质合金和TiAlN涂层刀具的10倍以上,且几种不同类型的金刚石涂层刀具寿命差异较小;金刚石涂层表面的晶粒细化可以降低加工表面的粗糙度和切削力,涂层脱落是金刚石刀具的主要磨损形式。      

Cr/Al/B/diamond体系中金刚石表面的热爆反应涂层

采用Cr/Al/B/diamond粉体为原料,并添加少量Cr₂O₃或B₂O₃以诱发热爆反应。结果表明:在高纯Ar保护下,热爆反应后的试样粉末化严重,易将结合剂与金刚石颗粒分离。添加Cr₂O₃的原料体系发生热爆反应后,结合剂中的主相为Cr₂AlB₂,金刚石表面会形成含Cr₃C₂和Al的复合涂层,涂层的晶粒大小为0.5～7.0 μm。当金刚石质量分数为10%和20%时,试样中的金刚石颗粒表面涂覆良好,其起始和终止氧化温度都显著高于未涂覆金刚石的;而在金刚石质量分数较高时,其表面涂覆效果略差。添加B₂O₃的原料体系发生热爆反应后,金刚石表面的涂覆效果不佳,只有半数或以下数量的金刚石颗粒被涂覆。