高钴硬质合金基底上化学气相沉积金刚石膜的研究

通过采用二步浸蚀法对硬质合金(WC-Co12％)刀具进行预处理，应用微波等离子化学气相沉积装置，在经二步浸蚀法预处理过的硬质合金上沉积出高质量和结合力强的金刚石涂层。研究了提高涂层附着力的基体预处理方法，用SEM、XRD、激光Raman光谱分析了涂层质量，用切削试验检测金刚石涂层与刀具基底的附着情况，结果表明二步浸蚀基体预处理方法能有效地降低基体表面金属钴的含量，消除沉积过程中Co的负面影响，从而提高金刚石涂层的附着力，使刀具使用寿命明显提高。     

硬质合金表面化学脱钴对金刚石涂层的影响

以CH3COCH3和H2为反应气源,采用热丝CVD法在经过一步法和碱酸两步法预处理的YG6硬质合金(WC-6％Co)基体上沉积了金刚石涂层.采用扫描电镜、能谱仪、硬度计等对样品进行了分析检测,着重考察了一步法和两步法化学腐蚀脱钴预处理工艺对硬质合金基体表面形貌、钴含量以及其对所得金刚石涂层的形核密度、晶粒尺寸、膜基附着性能等的影响.实验结果表明:无论是一步法还是两步法脱钴预处理工艺,都能去除YG6硬质合金基体表面的钴元素,一步法最佳腐蚀时间为15 min,两步法最佳腐蚀时间为5min,两步法效果强于一步法.在经两步法5min酸蚀脱钴预处理的YG6基体上,获得了膜基粘着性能良好、结晶性能好的微米金刚石涂层.     

CVD金刚石涂层硬质合金刀具研究进展

CVD金刚石涂层硬质合金刀具结合了金刚石和硬质合金的优异性能,是切削加工的理想材料,具有广阔的发展前景。当前限制CVD金刚石涂层刀具应用的主要问题是金刚石涂层与刀具基体之间的附着性能较差,其主要原因是粘接相Co对CVD沉积存在不利影响以及涂层与基体之间热膨胀系数存在较大差异。本文综述了提高界面结合强度和降低涂层表面粗糙度的方法,重点介绍了在界面添加过渡层来提高界面结合强度,并指出在硬质合金基体和CVD涂层之间添加过渡层和开发纳米CVD涂层是CVD金刚石涂层刀具今后的发展方向。     

化学气相沉积金刚石膜工业应用

成果成熟程度 已经解决在硬质合金衬底上生长均匀致密、附着 良好的金刚石膜的技术 成果的特点 金刚石薄膜涂层硬质合金工具由于性能优异、成 本相对较低(与PCD和金刚石厚膜钎焊工具相比)、可 以适应于复杂形状工具衬底沉积、以及可能大批量沉 积等优点,具有非常好的市场前景. 金刚石薄膜涂层硬质合金工具开发的关键是解决 金刚石薄膜在硬质合金衬底上的生长(沉积)和良好附 着的技术.本项目成果采用独特的衬底预处理和优化 的金刚石膜沉积工艺已经解决了Co对金刚石膜生长 和附着的有害影响问题.在YG类硬质合金工具衬底 所沉积的金刚石膜涂层厚度最大可达20～30μm.用洛 氏硬度压痕法评定的金刚石膜附着力时的无裂纹临界 载荷达1500N以上.在铣削A1-12wt%Si合金时,金 刚石薄膜涂层的YG6铣刀比未涂层硬质合金刀片使 用寿命可提高13倍以上.     

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。     

硬质合金工具的耐磨金刚石涂层

为了改善硬质合金刀具的耐磨性，采用U．S．E^TM工艺生产了高性能的多晶金刚石涂层。通过对WC-6Co％基体表面进行了预处理使得金刚石涂层与基体通过机械夹持作用产生很强的粘附力。用气蚀试验研究了微米结构和纳米结构的多晶金刚石膜的磨损性能。研究了金刚石结构(形态、晶拉度和晶粒取向、粗糙度)、涂层厚度以及涂层与界面之间的粘附性能对磨损机理的影响。在金刚石涂层工具的寿命和使用性能方面，纳米晶金刚石结构在工业应用上显示了很大的潜力。具有平滑表面的纳米结构金刚石比微米结构金刚石更适合做合适的基体(甚至形状复杂的预成形件)的涂层材料。通过增加涂层厚度，强度和断裂韧性等综合性能较好的薄膜(3μm)其优异的耐磨性能进一步提高。     

脱钴预处理对金刚石/硬质合金附着性能的影响

采用不同的两步处理方式浸蚀YG3和YG6低钴硬质合金基体表面，随后在热丝化学气相沉积装置上沉积了金刚石薄膜，分别用扫描电子显微镜、能谱仪以及洛氏硬度计对样品进行了分析检测。结果表明先采用Murakami剂30min腐蚀碳化钨相，再用3H2SO4 7H2O230s混合酸去除钴相，样品金刚石薄膜形核密度高，结晶质量较好，金刚石涂层与硬质合金基体结合良好。同一处理工艺，YG6系列样品处理效果更好。基体钴含量的降低对改善硬质合金与金刚石涂层间的附着性能有利。     

金刚石涂层用低钴硬质合金基体表面二步浸蚀法的研究

研究了先用Murakami剂浸蚀WC相，再用（H2O2＋H2SO4）酸混合液除去o相的2步法浸蚀YG6硬质合金基体表面预处理的过程，并在浸蚀过的硬质合金基体上，用热丝法沉积了金刚石薄膜，结果表明：2步浸蚀法可在基体表面深度为6μm-12μm的范围内，使Co含量从6％降低到0．54％－3．22％，并使硬质合金基体的表面粗糙度增加到Ra=1.0μm，但会导致硬质合金基体表面的硬度从89．9HRA降低至88．1HRA，在该硬质合金基体沉积金刚石薄膜之后，发现金刚石薄膜试样的组织结构具有明显的｛111｝面取向，金刚石涂层与硬质合金基体具有较高的粘结强度。     

硬质合金激光改性协同仿生微织构对硼掺杂金刚石涂层性能的影响

目的 研制应用于超精密加工领域的高性能金刚石涂层,探究硬质合金基体表面激光微织构对硼掺杂金刚石(BDD)涂层沉积质量的影响,分析不同类型的仿生微织构对基–膜结合强度、工具切削性能的改善效果及原因。方法 在硬质合金表面使用激光脉冲制备不同类型的仿生微织构,并通过热丝化学气相沉积(HFCVD)法在刀具表面沉积BDD涂层。采用数显洛氏硬度计(HRS-150)、超景深三维显微镜、扫描电子显微镜(SEM)、能谱仪(EDS)、白光干涉表面轮廓仪、拉曼光谱(Raman)对样品进行表征。通过压痕试验及铣削试验研究涂层的附着强度和刀具的切削性能。结果 激光微织构边缘发生表面硬化。激光微织构区域沉积BDD涂层后,基体表面缺陷显著降低,织构内部金刚石晶粒更密集,沉积质量提升,三角织构(TT)边缘的金刚石颗粒堆积坡度最缓,不同类型的织构化BDD涂层的粗糙度、金刚石纯度、切削性能及附着强度均不同,涂层附着力与表面硬度呈正相关。硼掺杂三角织构(BDTTD)涂层刀具具有最佳的切削性能。结论 织构边缘和内部具有更高的金刚石二次成核率和沉积质量。织构的存在可以提升BDD涂层的附着强度和刀具性能,并且织构边缘的涂层附着力最强,这些得益于激光烧蚀及仿生微织构对硬质合金表面的硬化及对BDD涂层内在缺陷的修复。     

金刚石薄膜与WC-Co硬质合金结合力的改善

利用SEM,XRD研究了Murakami溶液和H2等离子体处理对硬质合金表面形貌、物相结构的影响,并对硬质合金工具进行了复合金刚石薄膜涂层,采用压痕法和实际钻削实验检测了金刚石薄膜／基体间的结合力．结果表明,微米／纳米复合金刚石薄膜涂层分布均匀,具有低的表面粗糙度,Murakami溶液处理硬质合金可产生均匀的表面沟槽,其金刚石薄膜与基体间的临界载荷约为1．5kN,而用该方法制备的涂层钻头加工性能很差,H2等离子体处理促进了硬质合金基体表面的WC晶粒更加粗大、致密,其临界载荷超过1．5kN,用该方法制备的涂层钻头的加工性能优良。     

Wear and corrosion behavior of CrCN/CrN coatings deposited by cathodic arc evaporation on nitrided 42CrMo4 steel substrates

In the paper, the results of wear and corrosion tests of the CrCN/CrN multilayer coatings, formed by cathodic arc evaporation on 42CrMo4 (AISI 4140) steel substrates are presented. The substrates were subjected to thermo-chemical treatment–nitriding with various nitriding potential. The results of nitriding were determined by XRD and the hardness profile in the samples cross-section. The morphology of thin coatings was examined with SEM. A Vickers FV-700 and Fisherscope HM2000 hardness testers enabled to investigate hardness of steel substrates and CrCN/CrN coatings respectively. A pin-on-disc wear tests were used to determine the hardness and tribological parameters of the coatings: the coefficient of the friction and wear rate. The scratch test and Rockwell test were applied to assess the adhesion of the coatings to the substrates. The corrosion properties of coating–steel substrate systems were investigated using potentiodynamic polarisation tests. Corrosion potential, corrosion current density and polarization resistance were determined. It was found that that the nitriding of steel substrates improves properties of the coating–substrate system. The nitriding 42CrMo4 steel substrate with low nitriding potential enable to obtain substrates without surface “white layer” what favours good adhesion of the coating to the substrate. The CrCN/CrN multilayer coating–steel substrate systems show good mechanical and tribological properties and corrosion resistance.     

Effects of pre-treatments and interlayers on the nucleation and growth of diamond coatings on titanium substrates

During diamond deposition on titanium substrates, two processes exist: (1) diffusion of hydrogen into a titanium substrate and the formation of hydride thereby degrading the mechanical properties of the substrate; and (2) competition among the rapid diffusion of carbon atoms into substrates, the formation of carbide and the nucleation of diamond crystals (thereby affecting the nucleation and growth rate of the diamond coating). To increase the diamond nucleation rate and prevent the rapid diffusion of hydrogen and carbon into the substrate, different surface treatments and interlayers were studied in this paper. Results showed that polishing with diamond pastes and ultrasonic pre-treatment in diamond suspensions will significantly increase the nuclei density of diamond crystals. However, the diffusion of hydrogen into the substrate could not be prevented. Pre-etching of the titanium substrate using hydrogen plasma for a short time significantly increased the nuclei density of diamond crystals. Results showed that on a TiN interlayer, there was no significant improvement in diamond nucleation and growth, and the deposited diamond coatings showed poor adhesion. New diamond crystals were formed on the DLC interlayer in which DLC acted as the precursor for diamond nucleation. However, the so-formed diamond coating showed spallation. The plasma nitrided layer could prevent the rapid diffusion of hydrogen and carbon into the titanium substrate, but results showed a relatively low nucleation density of diamond crystals and poor adhesion. A graded interlayer combining plasma nitriding followed by plasma carbonitriding was effective in preventing the rapid diffusion of hydrogen and carbon into the substrate and improving the nucleation rate and adhesion of diamond coating.     

碳源浓度对CVD金刚石涂层质量的影响

在自制不锈钢钟罩式HFCVD设备上,以CH3COCH3和H2为气源,采用热丝CVD法在经过碱酸两步法预处理后的YG6硬质合金基体上制备了微米金刚石涂层;利用扫描电镜、Raman光谱仪、洛氏硬度计、维氏硬度计检测涂层的形貌结构、成分、附着性能和硬度,着重考察了碳源浓度对涂层质量的影响。结果表明过低碳源浓度造成涂层晶粒间存在缝隙,而过高的碳源浓度会使涂层晶粒细化,同时非金刚石相成分增加。以两步法工艺预处理基体,当碳源浓度为2%、沉积功率为4 kW、反应气压3 kPa、衬底温度为800℃、热丝基体距离为5 mm时,经4 h生长,可获得厚度为5.36μm、平均硬度HV为8 143.09、平均粒径1~2μm、纯度高、附着性能良好的微米金刚石涂层。     

钎焊金刚石耐磨涂层制备及其磨损性能

为提高农机刃具类零件的抗磨粒磨损性能,提出一种钎焊金刚石耐磨涂层制备方法,在Q235钢基体上制备了不同粒径及镀覆状态的金刚石耐磨涂层,并与65Mn钢的摩擦磨损和抗磨粒磨损性能进行对比。采用扫描电镜(SEM)对涂层表面、涂层与钢基体界面、涂层磨损后的表面微观形貌进行表征,并分析涂层的磨损规律及机理。结果表明:钎焊金刚石涂层与钢基体结合良好,金刚石在涂层中均匀分布,涂层厚度约370 μm。钎焊金刚石涂层的耐磨性优于65Mn钢的,且随着金刚石粒径减小钎焊金刚石涂层的摩擦系数降低,涂层的耐磨性增大;钎焊镀钨金刚石涂层的抗摩擦磨损和磨粒磨损性能均高于钎焊未镀覆金刚石涂层的。      

The Study of Deposition Parameters, Properties for PVD Ti_xN and Cr_xN Coatings Using a Closed Field Unbalanced Magnetron Sputter Ion Plating System

DIFFERENT PVD TECHNIQUES have been used todevelop a wide range of hard wear resistant coatings onsteel substrates since the early1980's.These coatingshave proved successful in improving the performanceof cutting tools[1].Closed field unbalancedmagnetron sputter ion plating(CFUBMSIP)is anexceptionally versatile technique,developed by TeerCoatings Ltd,for the deposition of high-quality;well-adhered thin films[2].Compared to other ordinarymagnetron sputter techniques,the CFUBMSIPt…     

The influence of composition and processing parameters on the mechanical properties and erosion response of Ni + TiB2 coatings

Sputtered Ni + TiB₂ coatings have been shown to protect Inconel* 718 and Ti-6A1-4V substrates from solid particle erosion. However, before new erosion-resistant coatings can be efficiently designed, it is essential that the role of mechanical properties in determining erosion resistance be fully understood. In this investigation, nanoindentation techniques were used to quantify the effects of substrate preparation, coating composition, and sputtering process parameters on the elastic moduli and indentation hardness of thin coatings deposited on Ti-6A1-4V and Inconel 718 substrates. The influence of these parameters on coating adhesion was determined using a conventional scratch test. Elastic moduli, indentation hardnesses, and coating adhesion were correlated with erosion behavior. The erosion resistance of those coatings that exhibited microscopic ductility is dependent on the nodule diameter and coating properties such as hardness, elastic modulus, and fracture toughness. Inconel 718 is a trademark of The International Nickel Co.     

A modified scratch test for the mechanical characterization of scratch resistance and adhesion of thin hard coatings on soft substrates

The scratch resistance of coatings and the adhesion between coating and substrate are usually determined in model experiments performed with sharp diamond indenters. These common methods as described for example in EN 1071-3 often fail for the combination of hard coatings on soft substrates due to very small critical loads or no detectable failure modes at all. Hence in the industry a lot of highly subjective and provisional test methods are used. On the one hand, quantitative comparability is difficult with common methods since defects already occur at very small loads for ductile and relative soft substrate materials like plastics. On the other hand, wear of the indenter in contact with hard coatings like pure diamond coatings requires its cost-intensive replacement.In this article a macroscopic tribological–mechanical test method is suggested which uses balls of hardened steel as indenters. A wide scope can be applied for both soft and hard coatings and different substrate materials. By variation of the ball-diameter, the normal contact force and the sliding speed different levels of stress and wear can be induced to analyze the tribological and mechanical behavior between body and counterpart as well as the interface of coating and substrate. To determine scratch resistance close to reality as usual scratch conditions on consumer products are better represented by a small ball than a sharp diamond indenter. Another benefit of the presented test method is the cost saving acquisition of the balls for indentation in very high quality as they are standard parts in the ball bearing industry. For every test on very hard coatings a new ball can be used with the possibility to detect the wear both on the base object and the counterpart. The occurring failure modes of coating and substrate also can be compared with comparatively easy numerical models to verify the results. Additionally to the test concept, first results of different coatings will be presented in this paper and compared with the results of common scratch tests.     

硬质合金表面渗硼处理对CVD金刚石涂层形成的影响

采用渗硼工艺对ＹＧ６硬质合金表面进行预处理,探讨了渗硼预处理对硬质合金金刚石薄膜涂层形成的影响。研究结果表明,渗硼时Ｃｏ在硬质合金表面同Ｂ形成ＣｏＢ、Ｃｏ２Ｂ化合物层。该硼化物层在金刚石沉积过程中,能有效阻挡硬质合金中粘结相Ｃｏ向表面扩散,消除了Ｃｏ对金刚石薄膜涂层形成时的不利影响,改善了薄膜涂层质量,提高了附着力。     

沉积温度对硬质合金金刚石涂层附着力影响的研究

采用压痕实验、扫描电镜与激光Raman光谱分析,实验研究了酸浸硬质合金基底上金刚石涂层的附着力随沉积温度的变化.结果表明,涂层质量随沉积温度降低而显著恶化,涂层应力则随沉积温度提高而上升.从提高涂层附着力的角度考虑,存在一个最佳沉积温度.在较低的沉积温度下,涂层自身的质量较低、力学性能较差,在载荷作用下易于破坏.提高沉积温度,涂层自身的质量可得到改善,但基底中的钴向基底表面扩散的倾向加大,而且热应力增大,会严重降低涂层与基底的附着力.除硬质合金基底的预处理工艺外,沉积工艺对金刚石涂层的组织、性能以及附着力均有重要影响.     

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.