双送粉激光熔覆CoCrAlSiY/YSZ梯度涂层微观组织及热振性能

采用双送粉方式,利用激光熔覆技术在TC4基体上制备CoCrAlSiY/Y2O3-ZrO2（YSZ）梯度涂层。对CoCrAlSiY/YSZ梯度涂层的微观组织、元素分布、显微硬度及热振性能进行了分析与研究,结果表明：梯度涂层与基体结合紧密,各梯度亚层之间不存在明显的界面,梯度涂层无明显裂纹,形成了良好的冶金结合;随着YSZ含量的提高,梯度涂层显微硬度呈梯度变化。在750 ℃下进行了不同循环周期的热振试验,试验结果表明CoCrAlSiY/YSZ梯度涂层具有一定的抗热振性。     

激光熔覆FeCoCrNiMox高熵合金涂层的组织和电化学腐蚀行为

采用同步送粉激光熔覆技术在27SiMn钢基体表面制备了FeCoCrNiMo_x高熵合金涂层，研究了Mo元素含量对FeCoCrNiMo涂层组织的影响。通过X射线衍射仪(XRD)、光学显微镜、扫描电镜(SEM)以及显微硬度计对熔覆层的微观组织结构和显微硬度进行观察和测试，且利用电化学工作站研究了熔覆层电化学腐蚀行为。研究结果表明：高熵合金涂层与基体贴合紧密，形成了良好的冶金结合。FeCoCrNiMo_0.25、FeCoCrNiMo_0.5高熵合金涂层主要由fcc相和σ相组成，涂层微观组织主要为柱状树枝晶，枝晶间富集Cr、Mo元素。FeCoCrNiMo_0.25高熵合金涂层在3.5%NaCl溶液呈现出明显的钝化行为，自腐蚀电流密度为7.84×10^-7A/cm²，显著优于基体材料，涂层表现出优异的耐腐蚀性能。     

C离子注入对硬质合金刀具TiN涂层性能的影响

在硬质合金刀具上沉积了PVD—TiN涂层,并采用C离子注入技术对其进行表面改性处理。对涂层截面的微观形貌、显微硬度以及与基体附着力的测试结果表明,C离子注入可使TiN涂层的显微组织细密均匀化,并能明显提高涂层的显微硬度以及与基体的附着力。     

钛材上火焰喷焊Ni-WC耐磨涂层的组织和性能

研究了在钛合金Ti-6Al-4V表面上采用火焰喷焊技术制备镍基碳化钨型自熔性合金涂层的可行性,利用SEM、XRD等手段分析了它的组织和性能。结果表明：采用火焰喷焊技术在钛合金表面上获得了功能梯度涂层,Ni-WC涂层为韧基体＋硬质相的耐磨组织,涂层和过渡层之间形成了韧性镍基合金层,在涂层、过渡层和基体之间形成了牢固的冶金结合,涂层的组织和显微硬度沿层深方向呈连续性和渐变性,喷焊表层中WC起到了主要的抗磨作用,涂层磨损失重仅为未喷焊钛合金的1／10。     

激光熔覆镍镀层的组织与性能

采用轴向横流CO_2激光器对Q235钢基体上刷镀的快速镍涂层进行激光熔覆,研究了激光熔覆前后涂层的显微组织和物相组成,测试了涂层的显微硬度。结果表明:激光熔覆消除了电刷镀镍镀层中的孔隙,提高了涂层的致密性,细化了晶粒,在涂层中形成了NiO相,它们的共同作用使涂层硬度显著提高;随激光功率提高,涂层晶粒得到细化,硬度得到提高。     

钢基体上化学气相沉积TiC涂层的显微组织及形成机理研究

本文通过对不同成分的钢试样,在不同的工艺条件下,化学气相沉积TiC 后的表面形态,显微组织及其变化的研究,提出了这种材料保护涂层的形成机理。通过对TiC 涂层与基体之间的过渡区组织的研究,论证了予先C-N 共渗,可以提高涂层与被保护材料基体的结合力这一观点。本项试验研究,对延长涂层使用寿命,进一步扩大TiC 化学气相沉积的实际应用等方面有所帮助。     

激光熔覆NiCrBSi/WC-Co复合涂层的组织与耐磨性能

采用同轴送粉激光熔覆技术在42CrMo合金钢基体表面制备WC-Co颗粒增强NiCrBSi复合涂层(NiCrBSi/WC-Co复合涂层),研究了复合涂层的物相组成、显微组织、显微硬度和耐磨性能。结果表明:复合涂层主要由γ-Ni固溶体、WC、FeNi_3、B_2Co_3、CoC_x、FeCr_(0.29)Ni_(0.16)C_(0.06)、W3_C、Co_3W_3C_6等物相组成;复合涂层顶部为方向杂乱的细小树枝晶,中部为较粗大的柱状树枝晶,底部为垂直于结合界面生长的胞状晶,涂层与基体形成了良好的冶金结合;复合涂层表面的平均硬度为810HV,远高于基体的(270HV),磨损质量损失为0.3mg,远低于基体的(1.9mg),其磨损机制主要为磨粒磨损;复合涂层可显著提高42CrMo钢基体的耐磨性能。     

化学气相沉积Ti(CN)/TiC/Al_2O_3多层涂层的结构和耐磨性能

采用化学气相沉积技术在42CrMo钢基体表面制备了Ti(CN)/TiC/Al2O3多层涂层,分析了多层涂层的断面形貌、元素分布和物相组成,并研究了多层涂层的显微硬度及其与基体的界面结合力、耐磨性能。结果表明:Ti(CN)/TiC/Al2O3多层涂层的结构较致密,主要由TiC0.2N0.8、TiC、α-Al2O3和Ti2O3组成,厚度约10μm,其显微硬度约2 654HV,涂层与基体间的界面结合力可达62N;与基体相比,多层涂层的平均摩擦因数约降低了23%,磨损量约减少了50%,其磨损机制为疲劳磨损和磨粒磨损。     

TiN/C3N4复合涂层的显微结构特征及其与性能的关系

利用扫描电镜和显微硬度及划痕试验对用反应磁控溅射法制备的TiN／C3N4复合涂层进行了较系统的研究，对TiN／C3N4复合涂层的横截面断口形貌进行了观察和分析。结果发现涂层呈平滑脆性断裂，并与呈韧性断裂的高速钢基体之间结合紧密，说明涂层具有很高的硬度和结合强度，能够满足刀具的使用要求。并对涂层的显微组织特征及其形成机理进行了初步讨论。     

TiC、TiN和Al_2O_3涂层硬质合金刀具的组织和磨损

本文介绍了在常用的C—6硬质合金刀具基体上的四种工业用涂层:①TiC;②TiC/TiCN/TiN;③TiC/Al_2O_3和④TiC/Al_2O_3/TiN的加工性能。对当切削速度为152米/分和213米/分时各种涂层刀具的后面磨损量和月牙洼磨损率作了比较。与其他涂层相比,TiC/Al_2O_3/TiN涂层刀具具有良好的耐磨性和抗月牙洼形成能力。下面按涂层成份和显微组织进行磨损率讨论。     

Tribological behavior of Fe-based bulk metallic glass

The unlubricated tribological characteristics of coating layers containing an Fe-based amorphous matrix have been investigated in air using an alumina ball with a diameter of 3.1 mm. From the ball-on-disk test system, the friction coefficient could be measured for up to 3,000 seconds. The temperature changes on the worn surfaces were also simultaneously measured using an infrared thermometer. Three different types of coating layers having an Fe-based amorphous matrix, an Fe-based amorphous matrix with embedded Ni-based self-fluxing alloy particles, and an Fe-based amorphous matrix with embedded WC particles were prepared through a high velocity oxy-fuel (HVOF) process. Although the coating layers have certain levels of porosity, unique frictional characteristics attributed to the amorphous matrix were observed during the friction tests. Compared with conventional bearing steels such as AISI 521000 (Hv=840), excellent tribological and wear characteristics were obtained, demonstrating that an Fe-based bulk metallic glass powder is a viable engineering material for practical anti-wear coating applications.     

微弧氧化电源占空比对陶瓷基自润滑复合涂层性能的影响*

为提高柴油机铝合金活塞的可靠性和耐用性,在不同电源占空比下通过微弧氧化实验在铝合金基体上制备得到微弧氧化陶瓷层,利用电泳技术将MoS_2微纳米粒子引入陶瓷层的孔隙中,制备得到陶瓷基自润滑复合涂层。研究微弧氧化电源占空比对陶瓷层和复合涂层微观形貌、厚度和表面粗糙度的影响,并利用往复式摩擦磨损试验机在干摩擦、油润滑条件下对复合涂层的摩擦学性能进行分析。结果表明:随占空比的提高,微弧氧化陶瓷层的厚度、表面粗糙度呈现先增加后减小的变化趋势;随占空比的提高,制备得到的复合涂层的摩擦因数先减小后增大,占空比为60%～70%得到的复合涂层摩擦因数最低,且复合涂层与基体结合状态好,抗磨自润滑性能显著。     

表面织构化喷涂涂层摩擦学性能的模糊综合评判

运用等离子喷涂技术制备涂层,在涂层上采用激光表面微造型技术制备各种不同形貌的表面织构。对涂层进行不同温度、不同表面织构、不同润滑剂含量下摩擦磨损性能试验,然后运用模糊综合评判法建立涂层评价指标集,并采用三角模糊数矩阵确定各个指标权重,建立涂层性能模糊评价模型,对等离子喷涂涂层各个影响因素进行综合评判。结果表明：该方法获得的最佳涂层与基于BP神经网络得到的结果一致,它为评定涂层优异性能提供一种直观的量化方案。     

金属复合CrN涂层的磨损性能及应用研究

为取代M2高速钢,降低空调压缩机叶片生产成本,在GCr15基体上分别沉积CrMoN和CrAlTiN涂层,采用XRD分析涂层的相组成,在MM-200试验机上对其进行摩擦磨损实验,用三维超景深显微镜测量其磨痕面积;并用SEM观察磨损后的磨痕形貌。结果表明:制备的CrAlTiN和CrMoN涂层都能在一定程度上提高基体GCr15的耐磨性能,其中CrMoN涂层是以单一的CrN面心立方结构存在,Mo起到置换固溶强化的作用,因此耐磨效果更明显;通过合理控制涂层厚度和提高膜基结合力,GCr15+CrMoN涂层很有希望能取代传统的空调压缩机叶片材料M2高速钢。     

Tribological Dependence of the High-Performance Ferrous-Based Coating on Different Coating Counterparts in Engine Oil

A ferrous-based coating with significant chromium was fabricated on aluminum alloy substrate using a plasma spray technique. The tribological performance of the as-fabricated ferrous-based coating sliding against different coatings including Cr, CrN, TiN, and diamond-like carbon (DLC) in an engine oil environment were comparatively studied. Results showed that the high hardness of the sprayed ferrous-based coating was achieved due to the dispersion strengthening effect of Cr₇C₃ phase embedded in the austenite matrix. The ferrous-based coating exhibited low friction coefficients when coupled with these four coating counterparts, which could be attributed to the boundary lubricating effect of engine oil. However, both friction and wear of the ferrous-based coating were different when sliding against these different coating counterparts, which might be closely related to the surface roughness, self-lubricating effect, and mechanical properties of the coupled coatings. Ferrous-based coating sliding against CrN and DLC coatings exhibited good tribological performance in engine oil. The best coating counterpart for the ferrous-based coating in an engine was DLC coating.     

纳米和微米La2O3颗粒增强镍基复合镀层的摩擦磨损性能

用复合电沉积工艺制备了纳米和微米La2O3颗粒增强镍基复合镀层，在销盘式滑动磨损试验机上考察了复合镀层在干摩擦条件下的摩擦磨损性能，用扫描电子显微镜分析了其磨损机理。结果表明：在干摩擦条件下，纳米La2O3颗粒增强复合镀层的摩擦磨损性能明显优于微米La2O3颗粒增强复合镀层；纳米La2O3增强镍基复合镀层的磨损主要表现为轻微磨粒磨损特征，而微米La2O3增强镍基复合镀层的磨损机制为剥层磨损和磨粒磨损。     

采用熔盐法在钼基体上制备硅化钼涂层的结构

采用熔盐法在钼基体上制备了硅化钼涂层,利用SEM、EDS和XRD等分析了涂层的显微结构、元素分布及物相组成,并研究了硅化钼的生成机制。结果表明:硅化钼是通过反应扩散形成的,涂层由外至内分别为MoSi2、Mo5Si3和基体;当熔盐中Na2SiF6和NaF两种活化剂共存时,涂层的厚度较大,1 000℃保温10h制备的硅化钼涂层的高温抗氧化性能相对较好;涂层厚度随温度的升高和保温时间的延长而增加,但温度的影响比保温时间的更显著。     

Role of Third Bodies in Friction and Wear of Cold-Sprayed Ti and Ti–TiC Composite Coatings

Titanium (Ti) and Ti-based alloy wear performance is often poor unless coating or lubricants are used. An alternative is to use hard phase reinforcement. Cold spray is a relatively new method to deposit composite coatings, where here we report the deposition of a Ti–TiC coating and its sliding wear behavior. Mixtures of mechanically blended Ti–TiC with various TiC content were injected into a de Laval nozzle and sprayed onto substrates. Two composite coatings and a pure Ti coating are reported here, where the as-sprayed compositions of the composites were 13.8 and 33.4 vol% TiC. Reciprocating dry sliding wear was performed using a custom-built in situ tribometer. All tests were conducted with a sliding speed of 3 mm/s and at a normal load of 0.5 N. Using a transparent sapphire hemisphere of 6.25 mm as counterface, dynamic behavior of third bodies was directly observed. It was found that adhesive transfer of Ti was the primary wear mechanism for the Ti coating, with oxidative and abrasive wear also occurring for longer sliding cycles. The superior wear resistance of the composite coatings compared to Ti was related to dual function of TiC particles, where they reinforced the Ti matrix and facilitated the formation of a stable and protective tribofilms. The tribofilms contained carbonaceous material that provided easier shear and lower friction. The formation of these tribofilms was highly dependent on the TiC particles, which contained excess carbon compared to the equilibrium composition. Higher TiC content was more effective in quickly developing and sustaining the tribofilms.     

Wear Behavior of Ceramic Powder and Solid Lubricant Cladding on Carbon Steel Surface

Thick composite coatings of carbides on a metal matrix are ideal for use in components that are subjected to severe abrasive wear. It is a metal matrix composite (MMC) that is reinforced by an appropriate ceramic phase, a solid lubricant coating to reduce friction and to protect the opposing surface. This study tested the wear behavior of a carbon steel surface after cladding by a gas tungsten arc welding (GTAW) method to enhance wear resistance. The microstructures, chemical compositions, and wear characteristics of the cladded surfaces were analyzed by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). The coating was uniform, continuous, and almost defect-free, and particles were evenly distributed throughout the cladding layer. The results of wear tests indicate that the friction coefficient of the TiC coating is lower than that of AISI 1020 carbon steel. Thus, the wear depth of the TiC coating is only one tenth of that exhibited by the AISI 1020 carbon steel. The experiments confirm that the cladding surfaces of TiC particles reduce the wear rate and friction.     

热浸镀55%铝锌合金镀层助镀剂的选择

用正交试验的方法研究了助镀剂对热浸镀55％铝锌合金镀层表面质量的影响，找出了较佳的助镀剂配方，并就助镀剂与表面的作用机理进行了探讨。推荐的助镀剂配方(在100ml溶液中)含：100gZnCl2 l5gAlCl3 5gLiCl 20gNH4Cl。经生产考核该配方的镀层质量较好，合格率提高15％。