YT类硬质合金成形铣刀的金刚石涂层工艺研究

针对YT15硬质合金B212型成形铣刀片,以两种不同的化学方式对硬质合金基体进行预处理,而后采用热丝化学气相沉积的方法在其表面沉积微米级金刚石薄膜.使用扫描电子显微镜观察金刚石薄膜颗粒的大小及均匀度,激光拉曼光谱仪检测金刚石涂层的成分,压痕法检验金刚石涂层刀片的膜-基附着强度,并就不同预处理的基体表面对金刚石薄膜的质量、附着性能的影响进行分析.结果表明,经预处理后的YT类硬质合金表面粗糙度较YG类降低约10%,采用平行布置热丝方式和现有的沉积工艺在YT类硬质合金衬底涂覆的金刚石薄膜均匀性较好,且经酸碱预处理的金刚石薄膜表现出良好的附着力,附着强度介于600~1 000 N,醇碱预处理对衬底表面原有的光洁度损坏较小,有助于细化金刚石晶粒,但膜-基附着强度不高.     

射频磁控溅射制备类金刚石薄膜

采用射频磁控溅射法在Si和Ti合金基体上沉积出类金刚石(DLC)薄膜.利用拉曼光谱仪、划痕仪和扫描电子显微镜分析了DLC薄膜的结构、膜基附着力和表面形貌.结果表明:射频磁控溅射法能够制备出表面平整、结构致密的DLC薄膜;同时基体材料的不同不会影响DLC薄膜的键合结构,Si基体上涂层附着力为30N,Ti基体上膜基结合力大于40 N.     

铜植入层对硬质合金上金刚石薄膜附着力的影响

金刚石薄膜在含Co的硬质合金刀具上的沉积有较大的困难,在化学气相沉积条件下碳在钴中溶解和扩散限制了金刚石的形核并易生成石墨,导致了金刚石薄膜的附着力较差,为增强金刚石薄膜在硬质合金刀具上的附着力,本研究采用了铜植入层作为扩散阻挡层,实验研究表明铜植入层提高了脱钴后的刀具表面的硬度及金刚石薄膜的质量;压痕试验表明：在载荷为1500N时金刚石薄膜的开裂直径为1．12mm,金刚石薄膜在刀具上的有很好的附着力。     

铜植入层对硬质合金上金刚石薄膜附着力的影响

金刚石薄膜在含Co的硬质合金刀具上的沉积有较大的困难.在化学气相沉积条件下碳在钴中溶解和扩散限制了金刚石的形核并易生成石墨,导致了金刚石薄膜的附着力较差.为增强金刚石薄膜在硬质合金刀具上的附着力,本研究采用了铜植入层作为扩散阻挡层.实验研究表明铜植入层提高了脱钴后的刀具表面的硬度及金刚石薄膜的质量;压痕试验表明:在载荷为1 500 N时金刚石薄膜的开裂直径为1.12 mm,金刚石薄膜在刀具上的有很好的附着力.     

Q235钢复合涂层腐蚀行为及微观组织研究

为探析舰船常用防护涂层的失效机制,制备了涂有环氧富锌底漆、环氧云铁中间漆和丙烯酸聚氨酯面漆的Q235钢板涂层试样,在盐雾下腐蚀1400h,用扫描电镜和能谱仪对涂层和基体金属表面的微观形貌、界面结构变化,表面缺陷,元素组成进行了研究.试验结果表明：盐雾腐蚀试验后,Q235钢表面涂层厚度增加,试样表面预制划痕处出现腐蚀,腐蚀产物呈片状,微观结构疏松,但涂层与基体在腐蚀后附着良好,涂层有良好的层间附着力,中间层和面层的防渗透性能保持在良好状态.     

采用Cu／Ti过渡层沉积金刚石薄膜刀具的界面结构

研究了硬质合金基底上Cu／Ti作过渡层化学气相沉积(CVD)金刚石薄膜的界面特性。利用激光Ra—man谱分析了过渡层不同生长阶段金刚石薄膜的质量的影响。采用SEM、EDS对金刚石薄膜硬质合金刀具横截面的结构进行了研究。结果表明：基体中的Co被Cu／Ti作过渡层有效的抑制住；Cu向基体内的扩散改善了基体的性能，提高了界面层金刚石薄膜的质量；Ti的引入促进了金刚石的形核，减少了界面处晶粒间的空隙，提高了金刚石薄膜与基体表面的实际接触面积。     

等离子喷涂梯度涂层的显微组织结构和性能

针对低散热发动机主要部件铝活塞顶部制备热障涂层的需要，用等离子喷涂法在铝基体上制备出梯度涂层，对其性能与显微组织结构进行了研究．抗热震实验结果表明，梯度涂层具有较高的结合强度．金相显微观测结果表明，梯度热障层结构致密，由基体至涂层表面。形成5种无宏观结合界面的成分呈梯度变化的组织结构．     

微波等离子体条件下硬质合金刀片中钴的扩散规律对金刚石涂层的影响

利用化学脱钴处理后的硬质合金刀片在微波等离子体条件下沉积金刚石薄膜,用电子能谱仪(EDS)检测发现经化学酸蚀处理后的硬质合金刀片表面的钴含量基本在0.3%左右,对于金刚石膜的形核及生长几乎没有大的影响,膜层致密、晶型良好;但是在长时间的高温沉积过程中,钴逐渐向表面扩散,如900℃条件下10h后刀片表面钴含量可达2.02%,可能对金刚石薄膜与基体之间的附着产生很大的影响,导致金刚石薄膜刀具使用使命的降低。     

镁合金表面热喷涂Al-Al2O3/TiO2梯度涂层研究

采用氧乙炔火焰喷涂法，在AZ91D镁合金表面制备Al-Al2O3/TiO2梯度涂层。利用扫描电镜和电子探针对涂层的组织形貌、成分进行了分析。采用热震法测试了涂层结合强度，并对涂层耐磨性进行了测试。实验结果表明：Al梯度层与基体及陶瓷涂层结合良好。涂层具有较高的硬度、耐磨性及抗热震性。     

金刚石薄膜基体材料的选择及预处理工艺

论述了CVD金刚石薄膜基体材料的性质,从基体材料与金刚石的热膨胀系数的差异、晶格失配等方面,提出了选择金刚石薄膜基体材料的方法,并对硬质合金、铜、钢、硅等材料的基体预处理工艺作了综述.指出基体材料的选择和预处理工艺是优质金刚石薄膜制备的关键.     

TiC涂层梯度硬质合金残余热应力分析

采用有限元方法分析有无梯度2种TiC涂层硬质合金的残余热应力,研究了残余应力随涂层及梯度层厚度的变化。结果表明:增加梯度层后,涂层内残余热应力的减小超过10%,合金中残余应力减小30%以上,表面残余应力也明显下降;随着涂层厚度的增加,涂层内拉应力大幅减小,剪切应力与等效应力略微增加,涂层梯度硬质合金的等效应力呈下降趋势;随着梯度层厚度的增加,涂层内残余应力减小,当梯度层厚度较大时,残余应力不再改变。因此,选择合适的涂层和梯度层厚度,涂层厚度一般为5～8μm,梯度层厚度控制在20μm左右,可以有效缓和残余应力,提高材料的结合强度。     

Microstructure and thermal properties of SiCp/Cu composites with Mo coating on SiC particles

SiCp/Cu composites with a compact microstructure were successfully fabricated by vacuum hot-pressing method. In order to suppress the detrimental interfacial reactions and ameliorate the interfacial bonding between copper and silicon carbide, molybdenum coating was deposited on the surface of silicon carbide by magnetron sputtering method and crystallized heat-treatment. The effects of the interfacial design on the thermo-physical properties of Si Cp/Cu composites were studied in detail. Thermal conductivity and expansion test results showed that silicon carbide particles coated with uniform and compact molybdenum coating have improved the comprehensive thermal properties of the Si Cp/Cu composites. Furthermore, the adhesion of the interface between silicon carbide and copper was significantly strengthened after molybdenum coating. Si Cp/Cu composites with a maximum thermal conductivity of 274.056 W/(m·K) and a coefficient of thermal expansion of 9 ppm/K were successfully prepared when the volume of silicon carbide was about 50%, and these Si Cp/Cu composites have potential applications for the electronic packageing of the high integration electronic devices.     

Thermal residual stress analysis of diamond coating on graded cemented carbides

Finite element model was developed to analyze thermal residual stress distribution of diamond coating on graded and homogeneous substrates. Graded cemented carbides were formed by carburizing pretreatment to reduce the cobalt content in the surface layer and improve adhesion of diamond coating. The numerical calculation results show that the surface compressive stress of diamond coating is 950 MPa for graded substrate and l 250 MPa for homogenous substrate, the thermal residual stress decreases by around 24% due to diamond coating. Carburizing pretreatment is good for diamond nucleation rate, and can increase the interface strength between diamond coating and substrate.     

Analysis on the Wear Performances of Cemented Carbide Tools Containing Ti in the Coatings When Machining Ti-6Al-4V Alloys

含钛涂层硬质合金刀具在加工Ti-6Al-4V合金时的磨损性能分析

孙剑飞1,2,3,杜大喜4,丁梓轩1,王凯1,白大山1,陈五一1,2

（1.北京航空航天大学 机械工程及其自动化学院,北京100191;

2.先进航空发动机协同创新中心,北京100191,中国;

3.北京市高效绿色数控加工工艺与装备工程技术研究中心,北京100191,中国;

4.北京航天石化技术装备工程有限公司,北京100166,中国）

摘要：由于钛元素的高亲和力,在加工钛合金时含钛涂层的硬质合金刀具似乎不是最佳的选择。然而在实践中,含钛涂层硬质合金刀具仍然广泛应用于钛合金的加工。为了系统的解释实践与理论之间的矛盾,进行了切削实验。使用俄歇电镜扫描切削区域来解析钛合金与硬质合金刀具之间的扩散过程。并通过分子热力学模拟Ti/Co扩散行为对这一过程进行仿真。实验和仿真结果表明,Ti/Co原子的相互扩散是导致扩散磨损的主要原因。溶解-扩散磨损是含钛涂层硬质合金刀具的主要磨损机制之一。此外,采用四种硬质合金刀具和另外两种金属陶瓷刀具以不同的速度切削Ti-6Al-4V合金,进一步验证含钛刀具在基体和图层中的高亲和力。实验结果表明,含钛硬质合金刀具一般不能用于钛合金的切削加工,但在合理的切削条件下,刀具与工件的亲和力较低。

关键词：磨损机理;Ti/Co扩散;分子热力学模拟;含钛硬质合金刀具;Ti-6Al-4V钛合金

     

Mierostrueture and Properties of Coating from Cemented Carbide on Surface of H13 Steel

The microstructures and properties of coating from cemented carbide on the substrate of H 13 by vacuum powder sintering were studied. The effect of sintering temperature on the microstructures of coating was discussed. The interface characteristics between coating and H 13 steel substrate, microhardness distribution and wear resistance in the coating were analyzed. The coating from cemented carbide with thickness of 1-3 mm by vacuum powder sintering at temperature ranging from 1280℃to 1300 ℃ was obtained. The experimental results indicated that the coating with microhardness of HV 1600 favorable to wear resistance is strongly bonded with the H 13 steel substrate by mutual diffusion and penetration of Fe,Cr, Mo,V in substrate towards the coating and W, Co,Ni in coating towards the substrate.     

Wear Mechanism of WC-Co Cemented Carbide Tool in Cutting Ti-6Al-4V Based on Thermodynamics

In order to optimize the tool coating material and reduce the tool wear rate,the coating material and wear mechanism for carbide tools are proposed and analyzed based on thermodynamics theory.We deduced the Gibbs free energy function method and analyzed the enthalpy value of the coating material of cemented carbide tools.The rules of diffusion wear and oxidation wear for WC-Co-based carbide tools were analyzed based on the diffusion dissolution theory and the calculation method of the thermal effect of chemical reaction.The diffusion wear and oxidation wear of WC-Co-based carbide tools when machining Ti-6Al-4V were studied with SEM-EDS.The results indicate that a good prediction accuracy of both diffusion wear and oxidation wear can be achieved by the method of thermodynamic theory analysis method.The conclusion will provide useful references for the optimization of cutting parameters and the improvement of the tool life.     

Carburized Effect on Gradient Cemented Carbide of TiC/TaC Prepared by Liquid Phase Sintering

The carburized graded cemented carbide with the addition of some(Ti,Ta) C was analyzed in detail.The micro-structure and element distribution were measured by using optical microscopy and X-ray photoelectron spectrometry along the gradient direction.The experimental results showed that a large amount of solid solution phases were formed and distributed like clusters in the surface layer of cemented carbide.The cobalt migration was not very notable and the Co-rich layer was close to the surface of cemented carbide.     

Microstructure and properties of gradient cemented carbide with Nano-TiN

Gradient cemented carbides with nano-TiN were prepared by the common powder metallurgical procedure. The formation of gradient zone and the microstructure, properties of the alloys were investigated using scanning electron microscope（SEM）, energy dispersive spectroscopy（EDS） and other performance testing apparatus. Moreover, the effect of nano-TiN on the gradient cemented carbide was studied. It is found that gradient zone width increases slightly with nano-TiN introduction. Both cobalt and titanium concentrations reach the maximum near the gradient border. Tungsten concentration shows fluctuation from the surface to the bulk. （Ti ,W）C phase grains are refined for nitrogen introduction. Core-rim structure has been observed under the SEM back-scattered mode. The core appears as dark due to more titanium in it and the rim with more tungsten appears as grey. In addition, the hardness and transverse rupture strength of gradient cemented carbide are enhanced with nano-TiN introduced.     

Morphology and Mechanical Characteristics of Monolayer and Multilayer Ir Coating by Double Glow Plasma

Multilayer iridium coating was manufactured on tungsten carbide substrates by a double glow plasma process.As comparison,monolayer was also produced.The microstructure and morphology were observed using scanning electron microscopy.Grain orientation and phase were determined using X-ray diffraction.The residual stress of the coating was studied by glancing incidence X-ray diffraction.The adhesive force of the coating was measured by a scratch tester.The results showed that both monolayer and multilayer had a polycrystalline phase with a strong(110) reflection.The coating had an excellent adhesion with no evidence of delamination.The adhesive force of the monolayer and multilayer was about 50 and 43 N,respectively.The interfacial reaction between the substrate and the layer occurred and a new WIr phase was found due to the high-temperature deposition process.The residual stress in the monolayer and multilayer was-1.6 and-1.1 GPa,respectively.