WC—Co硬质合金基体上金刚石薄膜的附着机理研究

金刚石涂层在硬质合金(WC-Co)基体上的附着力,是影响金刚石涂层刀具切削性能和使用寿命的关键因素.采用微波等离子体化学气相沉积(CVD)法在经酸浸蚀脱Co的硬质合金基体上生长金刚石薄膜.通过对金刚石膜/基界面的微观形貌和成分分析,初步认识了金刚石薄膜的附着机理:机械锁合作用对金刚石膜/基附着力有较大贡献;界面热应力和弱中间相的存在是导致金刚石膜自发剥离的主要原因.     

金刚石/碳化硅复合梯度膜制备研究

采用微波等离子化学气相沉积(MW-PCVD)制备金刚石/碳化硅复合梯度膜.工作气体为H₂,CH₄和Si[CH₃]₄(四甲基硅烷,TMS),其中H₂∶CH₄=100∶0.6,Si[CH₃]₄为0％-O.05％,沉积压力为3300Pa,基体温度为700℃,微波功率为700W.基体为单晶硅,在沉积前用纳米金刚石颗粒处理.沉积后的样品经扫描电子显微镜(SEM),电子探针显微分析(EPMA),X射线能量损失分析(EDX)表明:沉积膜中的碳化硅含量是随Si[CH₃]₄流量的变化而改变.通过改变Si[CH₃]₄的流量可以制备金刚石/碳化硅复合梯度膜,且梯度膜中金刚石与复合膜过渡自然平滑.     

用MPCVD法在WC—Co刀具上沉积金刚石薄膜

研究了硬质合金基体的预处理对金刚石沉积的影响,并确定了用MPCVD法在WC-Co刀具上沉积金刚石薄膜的工艺参数。采用了一些提高成核密度和沉积速率的方法,用SEM、XRD和Raman对金刚石薄膜的性质进行了分析。结果表明,合适的预处理可以有效的抑制钴的溢出并提高薄膜的质量。     

用MPCVD法在WC-Co刀具上沉积金刚石薄膜(英文)

研究了硬质合金基体的预处理对金刚石沉积的影响,并确定了用 MPCVD法在 WC－ Co刀具 上沉积金刚石薄膜的工艺参数。采用了一些提高成核密度和沉积速率的方法, 用 SEM、 XRD和 Raman对金刚石薄膜的性质进行了分析。结果表明,合适的预处理可以有效的抑制钴的溢出并提 高薄膜的质量。     

用热丝法在硬质合金基体上沉积金刚石膜的研究

用XRD，SEM和Raman光谱仪，洛氏硬度计等分析检测手段。研究了经表面两步法侵蚀后，YG15硬质合金基体上用热丝法沉积出的金刚石薄膜的晶体结构，显微组织，化学纯度及粘结性能等，结果表明，硬质合金基体表面一定深度范围内钴含量的变化。对金刚石薄膜的晶体结构取向，组织形态，化学纯度及粘结性能等有很大影响。（1）在基体表面深度约为5μm范围内，当钴含量为0.81%时，金刚厂长汪膜具有明显的{111}面取向，其金刚石纯度较高；而当钴含量为1.05%时，具有{110}和{111}面的混合取向，其金刚石纯度较低，且其薄膜具有较高的内应力。（2）当CVD沉积温度为800℃时，金刚石薄膜的晶粒度约为1-3μm。（3）与多边形金刚石薄膜相比，菱形金刚石薄膜与硬质合金基体具有较高的粘结性能。     

微波等离子体刻蚀处理对金刚石薄膜涂层刀具附着力和切削性能的影响

用HFCVD法在硬质合金（YG6）刀具衬底上沉积金刚石薄膜,用氢微波等离子体刻蚀的方法对衬底进行表面预处理,研究了该预处理技术对WC硬质合金衬底表面成分的影响,进一步探讨了所沉积金刚石薄膜的表面形貌和附着力,并通过难加工材料实际切削试验。研究了所制备的金刚石薄膜涂层刀具的切削性能。试验结果表明,Ar-H2微波等离子体刻蚀脱碳处理是提高金刚石薄膜附着力和改善涂层刀具切削性能的有效预处理方法。     

医用金属表面溶胶-凝胶法和离子束合成TiO2薄膜的结构、性能比较

采用溶胶-凝胶法和离子束增强沉积法在医用NiTi合金表面制备TiO₂薄膜以提高其生物相容性.利用X射线衍射（XRD）、原子力显微镜（AFM）和X光电子能谱（XPS）对薄膜的结构、表面形貌及组成进行了比较研究;电化学腐蚀实验表明,两种方法制备的TiO₂薄膜对金属基体均起到一种保护膜的作用,能够提高医用金属材料在模拟体液中的抗腐蚀性;对薄膜表面固定肝素抗凝血分子进行研究发现,溶胶-凝胶法制备的TiO₂薄膜表面能够获得较好的肝素固定效果.     

NiTi合金上沉积氮化碳薄膜的力学和血液相容性研究

采用磁控溅射法在生物医用NiTi合金基体表面制备了Ti/CN_x（x≈0.26）梯度薄膜,并制备了Ti/类金刚石(DLC)以及Ti/TiN薄膜进行对比研究. 利用显微硬度计、划痕仪比较分析了上述各薄膜的力学性能,通过表面接触角法研究了薄膜的亲水性. 着重测试并分析了溶血率和血小板粘附行为,进而对薄膜的血液相容性进行评估. 结果表明：Ti/CN_x梯度薄膜与NiTi合金基底的结合牢固,结合力达到63.6N. Ti/CN_x薄膜硬度为23.01GPa,和Ti/TiN薄膜硬度相当,略高于Ti/DLC薄膜. 溶血率和血小板粘附试验表明,Ti/CN_x梯度薄膜能有效改善NiTi合金基底的亲水性和血液相容性,与Ti/TiN和Ti/DLC薄膜相比,Ti/CN_x梯度薄膜具有最小的溶血率,仅为1.12％,并且无论在血小板的粘附数量还是在血小板变形程度都最少,因此具有良好的血液相容性.     

Si过渡层对梯度影响类金刚石薄膜结合力的影响研究

实验利用双放电腔微波-ECR等离子体源设备,采用复合PVD（physical vapor deposition）和PECVD（plasma enhanced chemical vapor deposition）的方法, 先后在NiTi基体上沉积Si和Si/α-C∶H过渡层,然后制备类金刚石薄膜.Raman光谱和透射电镜表明制备的梯度薄膜是典型的类金刚石薄膜,划痕的测试结果表明, Si过渡层沉积时间影响着梯度类金刚石薄膜与NiTi合金基体之间的结合强度,当沉积时间在60min左右时可获得具有最好结合强度的梯度薄膜,而超过或低于这个时间值会导致膜基结合强度降低.     

反应温度对LiCoO2薄膜性能的影响

采用水热电化学法在Ni基体上制备了LiCoO₂薄膜.反应温度影响薄膜的择优取向,80℃时制备的薄膜具有(003)取向,100℃制备的LiCoO₂薄膜具有(101)和(104)取向,150℃时制备的薄膜取向性不明显.其中以100℃制备的(101)取向LiCoO₂薄膜的电化学性能最好,其容量为143mAh/g;10次充放电后,薄膜电极容量衰减小.     

金刚石薄膜涂层硬质合金刀具的界面表征

采用SEM对金刚石薄膜涂层硬质合金刀具的金刚石薄膜表面、背面及金刚石薄膜剥落后的硬质合金刀片表面的典型形貌进行了观察,并采用TEM对金刚石薄膜／硬质合金刀片横截面的微观组织进行了研究,还采用FT—Raman光谱法对金刚石薄膜表面及金刚石薄膜剥落后的硬质合金刀片表面的微观结构进行了表征．结果表明：经适当的化学侵蚀脱钻和等离子体刻蚀脱碳预处理后,金刚石薄膜涂层硬质合金刀具的界面通常存在薄的（数十nm）石墨碳层;局部区域见到金刚石粒子直接生长在WC颗粒上,金刚石膜／基横截面的典型组织层次为：金刚石薄膜／薄的石墨碳层／细小的WC层／残留的脱碳层（η相＋W相）／原始的硬质合金基体．     

Adhesion improvement of diamond films on cemented carbides with copper implant layer

The deposition of diamond films on cemented carbides is strongly influenced by the catalytic effect of cobalt under typical deposition conditions. Decreasing the content of Co on the surface of the cemented carbide is often used for the diamond film deposition. But the leaching of Co from the WC-Co substrate leads to a mechanical weak surface, often causing poor adhesion. In this paper we adopt a copper implant layer to improve the mechanical properties of the Co leached substrate. The copper implant layer is prepared with vaporization. The diamond films are grown by microwave plasma chemical vapor deposition from the CH₄/H₂ gas mixture. The morphology and the quality of the diamond films have been characterized by scanning electron microscopy and Raman spectroscopy. A Rockwell apparatus has evaluated the adhesion of the diamond on the substrate. The results indicate that the diamond films have good adhesion to the cemented carbide substrate due to the recovery of the mechanical properties of the Co depleted substrate after the copper implantation and less graphite formation between the substrate and the diamond film.     

Microstructural control of boundary region between CVD diamond film and cemented carbide substrate

Effects of the composition, texture and pretreatment of cemented carbide substrates on the microstructure of the boundary region between CVD diamond film and the substrate were investigated using a microwave plasma CVD in the CO-H₂ system. Optimum CVD conditions for a uniform coating on to the edge part of cutting insert were: microwave power, 550 W; total pressure, 30 Torr; total flow rate, 200 ml/min; CO concentration, 5–20 vol%; treatment time, 3–5 h. An adherent and tough diamond coating was prepared by initial coating at lower CO concentrations and by subsequent coating at higher CO concentrations. A cemented carbide substrate in the binary WC-Co system which comprised fine-grained tungsten carbide and low content of cobalt was suited for preparation of adherent diamond coating. De-cobaltization pretreatment of the substrate surface in acid solution followed by an ultrasonic microflawing treatment enhanced the nucleation density and adherence of diamond film to the substrate. The rotation of substrate was found to be effective for increasing the uniformity and decreasing the grain size of diamond film.     

DEPOSITION OF DIAMOND FOR CUTTING TOOL APPLICATIONS

The poor adhesion of diamond film to substrates is one of the major problems for practical use in a cutting tool (1-4). in this study, sintered tungsten carbide (WC) body without Co metal, not cemented carbide, was used as the substrate (5), and the effects of surface decarburization of the substrate for improvement in the adhesion of diamond films were investigated. The surface decarburization and diamond coating were carried out in a microwave plasma CVD system. From the results of several adhesion tests, including the cutting tests, it is concluded that the good adhesion is obtained by surface decarburization of the substrate before diamond coating. The reasons for improvement in adhesion are considered by observing the interface structure between the film and the substrate. The damage mechanism of diamond coating on cutting an AI-18%Si alloy with increasing cutting speed is also discussed.     

Influence of WC-Co substrate pretreatment on diamond film deposition by laser-assisted combustion synthesis

The quality of diamond films deposited on cemented tungsten carbide substrates (WC-Co) is limited by the presence of the cobalt binder. The cobalt in the WC-Co substrates enhances the formation of nondiamond carbon on the substrate surface, resulting in a poor film adhesion and a low diamond quality. In this study, we investigated pretreatments of WC-Co substrates in three different approaches, namely, chemical etching, laser etching, and laser etching followed by acid treatment. The laser produces a periodic surface pattern, thus increasing the roughness and releasing the stress at the interfaces between the substrate and the grown diamond film. Effects of these pretreatments have been analyzed in terms of microstructure and cobalt content. Raman spectroscopy was conducted to characterize both the diamond quality and compressive residual stress in the films.     

Adhesion Enhancement of Diamond Films on Various Substrates by Carbide Interlayer

Diamond films were prepared on various substrates by a combustion flame technique using an oxyacetylene torch. During the deposition, a carbide interlayer was formed between the surface of the substrate and deposited diamond. The hard interlayers were seen on the molybdenum, tungsten as well as silicon substrates. The adhesion of diamond on the molybdenum substrate was improved with increase in the hardness of the carbide layer. This result strongly supports the premise that the carbide interlayer and/or carbon diffused layer enhances the adhesion of diamond to substrates.     

低压气相金刚石薄膜镀膜刀具膜/基附着性能压痕测试分析

低压气相金刚石薄膜硬质合金刀具在直流弧光放电等离子体CVD镀膜设备上制备.基底为YG6(WC-6%Co,质量分数)硬质合金刀具.采用洛氏(HRA)、表面洛氏(HRM)、维氏(HV)硬度试验机对所制备的金刚石薄膜刀具进行压痕测试;采用扫描电镜(SEM)观察压痕形貌并定性评价膜/基附着性能.结果表明:所制备的金刚石薄膜镀膜刀具的优选膜/基附着性能压痕测试方法是表面洛氏压痕法;优选测试条件为采用120°金刚石圆锥压头,测试加载载荷441N.     

Investigation of thick CVD diamond film with SiC interlayer on tungsten carbide for possible usage in geologic explorations

Diamond film on high-Cobalt containing tungsten carbide is explored for specific geologic explorations. A 153 μm thick diamond film was synthesized using a SiC interlayer, and its micro-structural and frictional properties were investigated accordingly. The results show that: (i) the film exhibits a well-grown and dense columnar structure in the depth direction, and its preferred crystallographic orientation lies at 2θ = 75.2° for the diamond plane (220); (ii) an approximately 7-μm-thick intermediate SiC layer between the film and substrate buffers Cobalt diffusion is evidently favorable for depositing diamond film; (iii) a sharp peak around 1332.7 cm⁻¹ in Raman spectra indicates that the film possesses the distinct diamond nature, and it is mainly composed of diamond crystallites in quality; and (iv) the average friction coefficients in three environments are 0.134 in dry friction, 0.0413 in oil lubrication, and 0.184 in mortar.     

Study on adhesion and wear resistance of multi-element (AlCrTaTiZr)N coatings

Multi-element (AlCrTaTiZr)N films were deposited on cemented carbide and M2 steel substrates by reactive RF magnetron sputtering. Prior to nitride film deposition, an interlayer between the film and the substrate was introduced to improve adhesion property. The influence of interlayer materials (Ti, Cr, and AlCrTaTiZr alloy) and interlayer thickness (0–400 nm) on the adhesion and tribological properties of films was investigated. In this study, the nitride film deposited at R_N = 20% exhibited the highest hardness (35.2 GPa) and the lowest residual compressive stress (? 1.52 GPa), and was prepared as the top layer for further testing. The interlayer materials can effectively improved the film adhesion onto the cemented carbide substrates, and the adhesive failure was not observed even under the normal load of 100 N. For M2 steel substrates, only the Cr interlayer can slightly improve the film adhesion, and the cohesive and adhesive failure can be found at relatively lower applied load. The optimal interlayer thickness was 100–200 nm for the 1 µm-thick (AlCrTaTiZr)N film and can be related to the stress evolution. The friction coefficient and wear rate for the (AlCrTaTiZr)N film were 0.82 and 4.9 × 10^? 6 mm³/Nm, respectively, and almost kept constant under different interlayer materials and thickness. The worn-through event of the nitride film during tribological test occurred easily owing to its poor adhesion behavior, and can be improved by interlayer additions.