等离子熔-喷WC-17%Co涂层的组织结构(I)

采用等离子熔-喷技术,在Q235钢表面制作了WC-17%Co金属陶瓷涂层,实现了涂层与基体为冶金结合的高结合强度涂层结构,从而解决了陶瓷涂层结合强度低的关键性难题。采用光学显微镜、SEM、TEM及EDS等方法,对熔-喷涂层接头形貌进行了分析研究。试验结果表明,熔-喷接头具有类似焊接接头的特征,是由涂层、熔合区、扩散区、热影响区所组成。熔-喷涂层与常规的喷涂涂层组织结构大不相同,组织结构比较复杂,主要由M6C(Fe3W3C或Co3W3C)、WC、γ-Fe、Co3O4、γ-Co、FeW3C、Fe2W和W2C等相组成,而且有规律地分布在涂层中的不同区域,根据组织结构的不同,涂层可分为表面层、中间冶金反应层和底层三个区域。     

等离子熔-喷WC-17% Co涂层的组织结构(Ⅰ)

采用等离子熔-喷技术,在Q235钢表面制作了WC-17%Co金属陶瓷涂层,实现了涂层与基体为冶金结合的高结合强度涂层结构,从而解决了陶瓷涂层结合强度低的关键性难题.采用光学显微镜、SEM、TEM及EDS等方法,对熔-喷涂层接头形貌进行了分析研究.试验结果表明,熔-喷接头具有类似焊接接头的特征,是由涂层、熔合区、扩散区、热影响区所组成.熔-喷涂层与常规的喷涂涂层组织结构大不相同,组织结构比较复杂,主要由M6C(Fe3W3C或Co3W3C)、WC、γ-Fe、Co3O4、γ-Co、FeW3C、Fe2W和W2C等相组成,而且有规律地分布在涂层中的不同区域,根据组织结构的不同,涂层可分为表面层、中间冶金反应层和底层三个区域.     

等离子熔-喷WC-17%Co涂层工艺参数对外观形貌的影响

等离子熔-喷技术同时具备等离子喷涂、熔焊技术的综合特点,可以实现各种陶瓷材料涂层与基体的冶金结合。Co基WC具有硬度高、耐磨损、耐腐蚀、耐高温等一系列优点。采用等离子熔-喷技术在Q235钢基体表面制备WC-17％Co涂层,通过研究等离子熔-喷工艺参数（等离子熔枪和喷枪角度、熔枪和喷枪与基材表面的距离、熔-喷速度、喷涂送粉量）对涂层外观形貌的影响,获得最佳的工艺参数,制备出外观形貌良好、无缺陷的熔-喷涂层。     

树脂基复合材料用陶瓷涂层防护性能分析

采用等离子喷涂铝粉作为打底材料在碳纤维增强聚酰亚胺复合材料（PMC）基体上制备了Al2O3和ZrO2轻质陶瓷防护涂层，测试了涂层的剪切结合强度、耐热循环性能、抗冲蚀性能、隔热性能。结果表明，等离子喷涂铝粉作打底层的涂层系统，性能优于电弧喷铝或电弧喷锌作打底层的涂层系统。带有Al2O3涂层的试样失重不到基体材料失重的1／3，Al2O3和ZrO2陶瓷涂层都可以为聚酰亚胺复合材料基体提供有效的冲蚀防护。Al2O3和ZrO2陶瓷涂层都可以为聚酰亚胺复合材料基体提供有效的隔热防护，ZrO2涂层隔热性能优于Al2O3涂层。     

纳米WC与CeO2对陶瓷涂层组织和性能的影响

以水轮机叶片的工作条件为背景,将纳米CeO2与纳米WC添加到Fe-WC金属陶瓷喷涂材料中,采用等离子喷涂方法制备涂层.对涂层进行显微组织分析及耐磨性和结合强度等试验,探讨纳米CeO2和纳米WC对喷涂层组织、耐磨性及结合强度的影响,以便制备性能优良的喷涂层用于水轮机叶片的保护,结果表明:将适量的纳米CeO2与纳米WC粉末添加到Fe-WC涂层中,可以改善喷涂层的组织,提高喷涂层的结合强度、耐磨性.     

激光熔覆等离子喷涂Al2O3陶瓷涂层组织结构研究

研究了45钢表面激光熔覆等离子喷涂Al2O3陶瓷涂层的组织结构、显微硬度及滑动磨损特性.结果表明,等离子喷涂Al2O3涂层的组织呈层片状,层间为机械结合,涂层由α-Al2O3, ZrO2和少量γ-Al2O3组成;激光熔覆Al2O3陶瓷涂层组织为细小枝状晶,由α-Al2O3及少量ZrO2组成.激光熔覆Al2O3涂层的显微硬度较高,滑动磨损时耐磨性明显优于等离子Al2O3喷涂层.     

纳米WC与Ce02对陶瓷涂层组织和性能的影响

以水轮机叶片的工作条件为背景,将纳米Ceo2与纳米WC添加到Fe-WC金属陶瓷喷涂材料中,采用等离子喷涂方法制备涂层。对涂层进行显微组织分析及耐磨性和结合强度等试验,探讨纳米Ce02和纳米WC对喷涂层组织、耐磨性及结合强度的影响,以便制备性能优良的喷涂层用于水轮机叶片的保护,结果表明：将适量的纳米Ce0,与纳米WC粉末添加到Fe-WC涂层中,可以改善喷涂层的组织,提高喷涂层的结合强度、耐磨性。     

晶须增韧等离子喷涂陶瓷涂层的可控制备与力学性能研究

针对新一代航空发动机和重型燃气轮机对长寿命、高韧性热障涂层的迫切需求,本文通过喷雾造粒法制备了长径比为10的ZrO2晶须复合YSZ喷涂粉末,采用SAPS技术制备了YSZ/ZrO2晶须増韧陶瓷复合涂层,对复合涂层的工艺参数进行优化,研究了熔融指数对陶瓷复合涂层微观结构的影响规律;通过狭缝法收集单个摊片的实验,阐明了ZrO2晶须增韧YSZ陶瓷涂层的形成机理,建立了晶须増韧陶瓷涂层的微观结构与热力学性能的内在关系。基于晶须弥散分布于复合涂层未熔颗粒区的特征,相比纳米结构YSZ涂层,YSZ/ZrO2晶须増韧陶瓷复合涂层的断裂韧性与热循环寿命均提高一倍。     

激光熔覆涂层与粉末火焰喷焊涂层比较

辽宁工程技术大学材料系分别采用激光熔覆与粉末火焰喷焊技术在45钢基体表面制备Ni60 20％WC台金涂层，比较其组织结构和性能，试验表明：激光熔覆涂层无缺陷、成品率高、组织细密均匀、晶粒细小、耐磨性能好、与基体结合为成分缓慢过渡的冶金结合。     

导卫辊用RE-WC-钢结硬质合金覆层材料的组织与性能分析

采用WC粉＋1Cr18Mn8Ni5N和改进的电弧喷涂技术在45钢基体上制备RE-WC．钢基复合涂层．然后利用氩弧熔覆工艺对其涂层进行熔覆，并对其显微组织、显微硬度和相结构进行了分析。结果表明。获得了由弥散分布的强化相增强的熔覆层，强化相主要是WC／W2C；熔覆层与基体之间为冶金结合；熔覆层硬度可达750HV0．1以上。     

Effect of Impact Angle on Ceramic Deposition Behavior in Composite Cold Spray: A Finite-Element Study

During the cold spraying of particle-reinforced metal matrix composite coatings (ceramic and metal particles mixture) on metal substrates, ceramic particles may either get embedded in the substrate/deposited coating or may rebound from the substrate surface. In this study, the dependence of the ceramic rebounding phenomenon on the spray angle and its effect on substrate erosion have been analyzed using finite-element analysis. From the numerical simulations, it was found that the ceramic particle density and substrate material strength played the major roles in determining the embedding and ceramic retention behavior. Substrate material erosion also influenced the ceramic retention, and the material loss increased as the impact angles decreased from normal. In general, the results concluded that decreasing the impact angle promoted the retention possibility of ceramics in the substrate. This study provides new theoretical insights into the effect of spray angles on the ceramic retention and suggests a new route toward optimizing the spraying process to increase the ceramic retention in composite coatings cold spray.     

FABRICATION AND PROPERTIES OF CERAMIC CEMENTED CARBIDE COMPACT INSERTS

１．ＩｎｔｒｏｄｕｃｔｉｏｎＭｅｔａｌｃｕｔｔｉｎｇｉｓｔｈｅｗｉｄｅｓｔｍａｃｈｉｎｉｎｇｍｅｔｈｏｄｉｎｍｅｃｈａｎｉｃａｌｉｎｄｕｓｔｒｙｔｏｄａｙａｎｄｃｕｔｔｉｎｇｔｏｏｌｓｐｌａｙａｎｉｍｐｏｒｔａｎｔｒｏｌｅｉｎｗｈｉｃｈ．Ｉｔｉｓｏｎｅｏｆｔｈｅｆａｃｔｏｒｓｔｈａｔｄｅｔｅｒｍｉｎｅｔｈｅｃｕｔｔｉｎｇｓｐｅｅｄａｎｄｍｅｔａｌｃｕｔｔｉｎｇｒａｔｅ．Ｃｅｒａｍｉｃａｎｄｃｅｍｅｎｔｅｄｃａｒｂｉｄｅａｒｅｔｗｏｖｅｒｙｉｍｐｏｒｔａｎｔｋｉｎｄｓｏｆｃｕｔｔｉｎｇｔｏｏｌｍａ…     

金属材料的激光陶瓷涂层和涂膜

介绍采用激光技术对金属材料沉积陶瓷涂层和涂膜的原理和工艺.获得的陶瓷涂层和涂膜可以改善金属材料的表面性质并赋予其特殊的性能.     

Electrolytic plasma processing for cleaning and metal-coating of steel surfaces

Electrolytic plasma processing (EPP) involves electrolysis and electrical discharge phenomena and it is an emerging, environmentally friendly surface engineering technology. Electrolytic-plasma/material surface interactions during processing can be used for cleaning of metal surfaces, formation of diffusion layers and/or deposition of metal, ceramic and composite coatings. The present work was concerned with cleaning and deposition of metal coatings on steel surfaces for corrosion protection. The effects of processing parameters on (i) cleaning steel surfaces (oxides and contamination); and (ii) Zn and Zn–Al coating deposition were investigated. Surface roughness and oxygen content prior to and after cleaning were evaluated by profilometry and energy dispersive X-ray analysis (EDAX), respectively. The structure of the EPP cleaned outer surface layer as it evolves after the electrolytic–plasma interaction was studied by high resolution TEM. Morphology, microstructure, composition, adhesion and density of EPP-deposited Zn and Zn–Al coatings on cleaned surfaces were studied as a function of processing parameters. Corrosion properties of the cleaned and coated steels were evaluated by corrosion potential and potentiodynamic polarization measurements. The results show that EPP can effectively produce clean surfaces and also metal and alloy coatings at high deposition rates, and it has a great potential as a new plasma surface engineering technique.     

Reactive thermal spray by high velocity ceramic jet and characterization of the coatings

A ceramic jet composed of molten particles in an electrothermally exploded powder spray was identified by the flash, soft x-ray radiography technique. The velocity of the leading edge of the jet was estimated to be 900 m/s. The coating obtained by a ceramic jet of titanium diboride consisted of a mixing layer of the substrate material and sprayed ceramics. A coating, which exhibited no pores or cracks, was formed through the dense deposition and solidification of spray droplets. The successive impacts of the droplets caused melting and stirring of the substrate surface to form a mixing layer. Some of these layers were formed due to capillary movement of the molten substrate material into the fractures of coarse ceramic particles. Thermal spray by chemical reaction between titanium and boron nitride particles resulted in a composite coating of TiN and TiB₂. The character of the mixing layer indicated that the depth profiles depended on the substrate material.     

Material and geometrical design for high reliability bilayer

Ceramic/metal, ceramic/ceramic, and ceramic/polymer bilayers are prepared to find the best design for a reliable material. The transparent bilayer enablesin situ observation of crack initiation. The elastic modulus of the substrate material in the bilayer is controlled from 2.35 GPa to 230 GPa by using different compositions of glass, metal, and polymer. The thickness of the ceramic coating layer is controlled from 120 μm to 5.6 mm. The surface of the coating material is abraded to control the strength and toughness. Classical cone cracks and transverse radial cracks are observed during Hertzian indentation. The crack initiations depend on not only material design parameters such as strength, toughness, and elastic modulus but also geometrical parameters such as coating thickness. Conditions for avoiding cracking are considered, in terms of the material and geometrical design parameters.     

NiAl/NiCoCrAlY/8YSZ复合喷涂层的微观结构与性能研究

目的提高金属/陶瓷隔热涂层体系在海洋环境下的耐腐蚀性能。方法利用冷喷涂方法制备NiAl复合打底层和Ni CoCrAlY粘结层,与等离子喷涂制备的8YSZ陶瓷层构成适用于海洋环境的多层结构耐蚀隔热涂层体系。利用FE-SEM分别观察喷涂态粘结层和陶瓷层的表面、横截面形貌,通过EDS分析涂层元素分布;利用XRD分析表征涂层的物相组成;借助万能材料试验机,采用拉伸法测试涂层结合强度;利用热循环试验和焰流冲刷试验测试涂层的耐高温性能。结果微观分析表明,冷喷涂制备的NiAl复合打底层和Ni CoCrAlY粘结层形貌致密,涂层材料未发生明显氧化,颗粒变形程度不一,粘结层与基体间的结合强度约为18.4 MPa,粘结层与8YSZ陶瓷层界面结合紧密。陶瓷层物相结构和成分稳定,涂层经12次热震循环和1000个周期的高温焰流冲击后,表面未出现开裂、起皮和脱落。结论采用冷喷涂法和等离子喷涂法联合制备的耐蚀隔热复合涂层体系具备良好的耐热性和耐腐蚀性。冷喷涂制备的金属涂层结构致密,孔隙率低,与陶瓷层结合良好,能够有效提高涂层体系在腐蚀性环境中的耐蚀性能。NiAl复合涂层可以缓解Ni CoCrAlY粘结层和铝合金基材间的热匹配问题,增强涂层的结合性能。     

金属材料表面纳米化研究与进展

大多数金属材料的失效都是从其表面开始的,进而影响整个材料的整体性能。研究表明,在金属材料表面制备纳米晶,实现表面纳米化,可以提升材料的表面性能,延长其使用寿命。金属材料表面纳米化是指利用反复剧烈塑性变形让表层粗晶粒逐步得到细化,材料中形成晶粒沿厚度方向呈梯度变化的纳米结构层,分别为表面无织构纳米晶层、亚微米细晶层、粗晶变形层和基体层,这种独特的梯度纳米结构对金属材料表面性能的大幅度提升效果显著。根据国内外表面纳米化的研究成果,首先对表面涂层或沉积、表面自纳米化以及混合纳米化3种金属表面纳米化方法进行了简要概述,阐述了各自优缺点,总结了表面自纳米化技术的优势,在此基础上重点分析了位错和孪晶在金属材料表面自纳米化过程中所起的关键作用,提出了金属材料表面自纳米化机制与材料结构、层错能大小有着密不可分的联系,对金属材料表面自纳米化机制的研究现状进行了归纳;阐明了表面纳米化技术在金属材料性能提升上的巨大优势,主要包括对硬度、强度、腐蚀、耐磨、疲劳等性能的改善。最后总结了现有表面强化工艺需要克服的关键技术,对未来的研究工作进行了展望,并提出将表面纳米化技术与电镀、气相沉积、粘涂、喷涂、化学热处理等...     

Adhesion of Ceramic Coating on Thin and Smooth Metal Substrate: A Novel Approach with a Nanostructured Ceramic Interlayer

The adhesion of plasma-sprayed coating is, to a large extent, controlled by the cleanness and roughness of the surface on which the coating is deposited. So, most of the plasma spray procedures involve surface pretreatment by grit-blasting to adapt the roughness of the surface to the size of the impacting particles. This preparation process brings about compressive stresses that make it inappropriate for thin substrates. The present works aim to elaborate a thick ceramic coating (about 0.5?mm thick) on a thin metal substrate (1?mm thick) with a smooth surface (Ra of about 0.4???m). The coating system is intended for use in a Generation-IV nuclear energy system. It must exhibit a good adhesion between the ceramic topcoat and the smooth metal substrate to meet the specifications of the application. Our approach consisted of depositing the ceramic topcoat by air plasma spraying on a few micrometers thick ceramic layer made by suspension plasma spraying. This nanostructured layer played the role of a bond coat for the topcoat and made it possible to deposit it on the as-received substrate. The adhesion of the nanostructured layer was measured by the Vickers indentation cracking technique and that of the ceramic duplex coating system by tensile test.     

激光熔覆镍基合金和Ni/WC涂层的磨损特性

采用热喷涂方法预置0．5mm厚度的涂层，研究在激光熔覆过程中不同的激光功率对涂层组织特性的影响，对镍基合金涂层和Ni/WC陶瓷涂层进行耐磨实验，结果表明，两种涂层存在不同的磨损特性，WC陶瓷颗粒在涂层及其表面的均匀分布可提高涂层的耐磨性，硬度和韧性的相互匹配是提高材料磨性的有效方法。