Lubrication properties of silver-palladium alloy prepared by ion plating method for high temperature stud bolt

As a solid lubricant, silver-palladium (Ag-Pd) alloy coating was investigated for the application to high temperature stud bolt. A glue layer nickel (Ni) film was deposited on the surface of the hex bolt sample and then Ag-Pd alloy coating was performed on it using ion plating method. The friction coefficient of Ag-Pd alloy film coated bolt was lower than that of N-5000 oil coated bolt by the result of axial force measurement. The cyclic test of heat treatment was conducted to evaluate the durability of Ag-Pd alloy film coated bolt. In a cycle, sample was assembled into the block using torque wrench, followed by heating and disassembling. It was not successful to disassemble the N-5000 oil coated bolt from the block after only one cycle. However, the Ag-Pd alloy film coated bolt was able to be disassembled softly till 12 cycles.     

Silver-palladium alloy deposited by DC magnetron sputtering method as lubricant for high temperature application

The silver-palladium(Ag-Pd) alloy coating as a solid lubricant was investigated for its application to the high temperature stud bolts used in nuclear power plants. A hex bolt sample was prepared in the following steps: 1) bolt surface treatment using alumina grit blasting for cleaning and increasing the surface area; 2) nickel(Ni) film coating as a glue layer on the surface of the bolt; and 3) Ag-Pd alloy coating on the Ni film. The films were deposited by using a direct current(DC) magnetron sputtering system. The thickness and composition of the Ag-Pd alloy film have effect on the friction coefficient, which was determined using axial force measurement. A 500 nm-thick Ag-Pd (80:20, molar ratio) alloy film has the lowest friction coefficient of 0.109. A cyclic test was conducted to evaluate the durability of bolts coated with either the Ag-Pd (80:20) alloy film or N-5000 oil. In a cycle, the bolts were inserted into a block using a torque wrench, which was followed by heating and disassembling. After only one cycle, it was not possible to remove the bolts coated with the N-5000 oil from the block. However, the bolts coated with the Ag-Pd (80:20) alloy could be easily removed up until 15 cycles.     

耐海洋环境中霉菌腐蚀有机涂层的研究

为了提高铝合金耐海洋环境中霉菌腐蚀的性能,先在铝合金表面涂覆硅烷膜作为过渡层,然后在硅烷膜上涂覆成分配比不同的有机硅改性环氧树脂涂料.对比研究了涂层的表面形貌、相组成及霉菌腐蚀的性能.并探讨了涂层与基体的结合机理.结果表明:硅烷膜与铝合金基体、有机涂层之间发生了化学反应,使涂层与铝合金基体结合良好;按有机硅改性环氧树脂...     

低温共烧用可焊浆料用银钯合金粉特性研究

银钯合金粉末制备的电子浆料以其优异的导电、抗银离子迁移、可焊耐焊性,成为低温共烧陶瓷工艺(LTCC)配套用关键电子浆料之一。比较研究两种不同特性的银钯合金粉制备的浆料与Ferro A6生瓷带共烧后的匹配性、电学性能、附着力、可焊性与耐焊性等性能。高振实、大粒径的银钯合金粉制备的浆料与Ferro A6生瓷带共烧平整,电极膜层平整光滑,各项性能表现出优异。粒径较小的银钯合金粉,与瓷料烧结收缩率不匹配,基板翘曲严重,膜层起皱,导电性及可焊耐焊性相对较差。     

Anticorrosive magnesium phosphate coating on AZ31 magnesium alloy

A novel anticorrosive film with a thickness of approximately 50 μm was successfully coated on an AZ31 magnesium alloy by chemical and low-heat treatments (50 °C). The film was a single-phase system of newberyite (MgHPO₄•3H₂O) having an orthorhombic crystal structure. The corrosion current density of the newberyite film coated on the AZ31 magnesium alloy decreased by more than two orders of magnitude as compared to that of the AZ31 magnesium alloy. The static water contact angle of the newberyite film was less than 10°. The average value of the scratch critical load for the newberyite coating was estimated to be approximately 15 mN.     

Corrosion fatigue behavior of epoxy-coated Mg–3Al–1Zn alloy in NaCl solution

The corrosion fatigue behavior of epoxy-coated Mg–3Al–1Zn alloy was investigated in air and 3.5 wt%NaCl solution. Epoxy coating as a new method was used to improve the corrosion fatigue property of the material.Results show that the fatigue limit(FL) of the coated specimens is higher than that of the uncoated specimens in3.5 wt% NaCl solution because of the strengthening and blocking functions of the epoxy coating. The FL of the coated specimens in 3.5 wt% NaCl solution is as high as that in air. It implies that the coated specimens are not as sensitive to the environment as the magnesium alloy. The low tensile strength and the short elongation of the pure epoxy coating lead to that the fatigue crack of the coated specimen is always initiated from the epoxy-coating film Pores and pinholes accelerate the fatigue crack initiation process. Pinholes are caused by the corrosion reactions between the epoxy coating and the NaCl solution.     

Ti Coating on Magnesium Alloy by Arc-Added Glow Discharge Plasma Penetrating Technique

MAGNESIUM is the8th most abundant element on theearth.Because of that it has some advantageousproperties such as high ratio of strength/weight with adensity that is only2/3that of aluminum and1/4that ofiron,high ratio of rigidity/mass,special characteristicsof electromagnetic shield and shock absorption,excellent cutting and polishing performances,magnesium alloys have been used widely by widely inmany manufacturing industries including aerospace,automobile,electronics and so on.But there i…     

镁合金表面Ni+C涂层的耐腐蚀与耐磨性能研究

目的提高镁合金表面的耐腐蚀和耐磨损性能。方法采用非平衡磁控溅射离子镀技术与化学镀技术相结合,在GW83镁合金表面制备Ni+C复合膜层。通过扫描电子显微镜和拉曼光谱分析了薄膜的形貌、成分和结构。利用电化学和浸泡后ICP-AES测试,评价了该复合碳膜涂层的耐腐蚀性能。同时采用摩擦磨损试验获得Ni+C复合膜层的磨损寿命。结果 Ni+C复合膜层致密均匀,表面孔隙率极低,表面碳层为典型的类石墨膜并且含有大量的无序结构。相对于GW83镁合金来说,Ni+C复合膜层的存在导致在3.5%Na Cl溶液中的腐蚀电位正移了301 m V,腐蚀电流密度从186μA/cm2降低至11μA/cm2。浸渍后ICP-AES试验显示,Ni+C涂覆的镁合金GW83的金属离子释放量更低。摩擦磨损试验表明,Ni+C涂层的磨损寿命为7000 s,与镁合金基体相比,Ni+C复合涂层极大地提高了其磨损寿命。结论在该Ni+C复合膜层中,表面碳层较致密,与Ni层结合良好,显著提高了基体的耐腐蚀性能。此外由于存在较厚的Ni中间层,对膜层起到了较大的支撑作用,Ni+C复合膜层从而延长了基体镁合金的磨损寿命。     

TC4表面沉积Nb涂层在模拟体液环境下的电化学性能研究

利用双阴极等离子溅射技术在Ti-6Al-4V (TC4)合金表面沉积Nb涂层,采用XRD、XPS和SEM研究涂层的组成及横截面形貌,并采用电化学工作站对涂层与基体的电化学性能及其钝化膜半导体特性进行研究.电化学测试均在模拟人体体液环境的Ringer's溶液中37℃下进行.结果 表明,Nb涂层厚度约为18 μm,无孔洞、...     

铸铝合金组合件阴极电泳涂装漆膜缩孔产生原因与解决方法

目的解决铸铝合金组合件阴极电泳涂装后漆膜产生缩孔的问题。方法通过分析阴极电泳涂装后漆膜产生缩孔的原因,调整工件前处理脱脂工段、化成工段和电泳工段的槽液参数,延长脱脂时间,再经180 V电压涂装成膜,最后烘烤固化。结果经检验,工件漆膜平整光滑,缩孔消除,耐盐雾性能达1000 h,漆膜综合性能满足产品验收要求。结论通过调整铸铝合金组合件前处理工艺和电泳涂装施工参数,可消除漆膜缩孔,提高弹药整体防腐性能。     

液相Al-Si共渗提高Ti3Al基合金高温抗氧化性

使用Al-8Si（mass %）合金熔体对Ti3Al基合金表面进行液相Al-Si共渗硅处理，在表层发生了不同程度的界面反应，经X射线能谱分析和对涂层的X射线衍射分析，推断涂层由TiAl3及Ti-Si化合物组成.经1 013 K/6 min+983 K/10 min的二次改性处理，可明显改善Ti3Al基合金的高温抗氧化性.1173 K/100 h氧化后的涂层组织，分析表明，涂层改善基体抗高温氧化性的根本原因是在最外层生成了一薄层致密的Al2O3膜.相关机理还有待更深一步研究.     

Microstructure and wear properties of silicide based coatings over Mo–30W alloy

The paper deals with the microstructure and wear properties of the Mo-30W alloy, coated with silicide based oxidation resistant coatings using pack cementation technique. The microstructure of the coating revealed that the coating was free of cracks or pores, adherent to the substrate and comprised of either single layer or double layer depending the coating temperature. Scanning electron microscopy (SEM) coupled with energy dispersive spectroscopy (EDS) was used to determine diffusion profiles for Mo, W and Si. Reciprocating sliding wear and friction experiments were performed on the uncoated and coated alloy. Double layer coating showed an improved friction coefficient as compared to base alloy as well as a single layer coated alloy. The wear tests also showed a marked improvement of wear resistance of coated alloy as compared to uncoated alloy. The coating was found to be wear resistant at 7 N.     

磷酸钙表面改性镁合金的生物腐蚀性能及细胞相容性(英文)

在镁合金表面制备磷酸钙涂层,利用X射线衍射仪确定涂层的相组成。用扫描电镜观察涂层的微观形貌。结果表明,涂层由板条状的CaHPO4·2H2O晶体组成。采用电化学测试和浸泡实验研究磷酸钙改性镁合金的生物腐蚀性能,并与未改性合金进行对比。通过观察L929细胞在材料表面的粘附生长状况来评价材料的生物相容性。电化学测试结果表明,磷酸钙改性镁合金比未改性合金显示出更好的耐腐蚀性能。浸泡实验表明,磷酸钙涂层可以减缓合金的腐蚀,且在浸泡过程中磷酸钙涂层发生了向羟基磷灰石(HA)的转变。与未改性合金相比,L929细胞在磷酸钙改性镁合金表面显示出良好的粘附、生长和分化特征,表明磷酸钙改性能明显提高基体合金的细胞相容性。     

镁合金表面加弧辉光离子渗镀Ti的腐蚀性能研究

加弧辉光离子渗镀技术将辉光放电与弧光放电有机地结合起来,利用辉光放电空心阴极效应使工件迅速升温,同时在真空容器壁上设置一个或多个金属阴极电弧靶源,利用真空电弧放电而不断地发射出高能量、高电流密度、高离化率的欲渗金属离子流,依靠扩散和离子轰击作用快速渗入工件表面层,在工件表面可以形成渗层、镀层、渗镀结合层.在实验条件下对镁合金AZ91表面渗镀了Ti,采用极化曲线测试和盐雾实验分析了处理后材料的腐蚀行为,用扫描电镜（SEM）分析了Ti镀膜的表面形貌,用电子衍射光谱（EDS）和辉光放电光谱仪（GDS）分析了表面化学成分分布.结果表明渗镀Ti显著提高了AZ91的耐腐蚀性.     

Characteristics of Ni-Ir and Pt-Ir hard coatings surface treated by pulsed Nd:YAG laser

The subjects of the presented paper are to develop a laser surface treatment technology for the protective coatings of glass-molding dies and to better understand the interaction between laser beam and materials coated on the die surface. A variety of alloy films, including Ir-25 at.% Pt, Ir-50 at.% Pt, Ir-75 at.% Pt, Ir-25 at.% Ni, Ir-50 at.% Ni, and Ir-75 at.% Ni compositions are deposited by the ion source assisted magnetron sputtering system (ISAMSS). A Cr layer that functioned as a buffer layer is deposited between the alloy film and die surface. After an alloy film and the buffer Cr layer were sequentially coated on tungsten carbide (WC) surface, Nd:YAG laser was directly applied in the writing process. The temperature profile of the film stack structure is simulated by ANSYS software. The surface roughness was analyzed by atomic force microscopy (AFM) to compare the coating surface roughness before and after the laser surface treatments. The treated coatings for oxidation prevention test were examined by energy dispersive x-ray spectrometry (EDS). Nanoindentation instrument was performed to evaluate microhardness and reduced modulus of the coatings. The cross-sectional structures between the hard coating layer and buffer layer were also inspected by a scanning electron microscope (SEM). The Pt-Ir and Ni-Ir film coatings are unable to withstand the working temperature over 1500 °C, which is considered for quartz molding process and hot embossing process. The films showed high roughness, low microhardness and low reduced modulus because the film oxidation occurred in a high working temperature process.     

双峰结构Mo-Si-B基体表面多层硅化物涂层的表征和抗氧化性能

由于在细晶Mo-Si-B合金中制备双峰分布的α-Mo晶粒能够在不显著降低合金强度的前提下大幅提高其断裂韧性,为了加强双峰结构合金的表面防护,同时保持其优异的力学性能,通过包埋渗在合金表面上制备了一个具有多层结构（MoSi₂,Mo₅Si₃和Mo₅SiB₂/MoB）的涂层。研究结果表明,相比在细晶结构基体上制备的涂层,双峰结构基体上的涂层表面较为粗糙,并且也表现出双峰分布的微观组织。此外,覆盖涂层后的双峰结构合金的断裂韧性依然良好,并且分布在涂层中的La₂O₃颗粒能够增韧涂层。具有涂层的双峰结构合金在1100~1300 ℃下展现出了卓越的抗氧化性,这是由于氧化过程中在涂层表面快速形成了一个薄且能自愈合的SiO₂-B₂O₃膜。随着氧化温度升高,SiO₂-B₂O₃膜的粘度降低,使得SiO₂-B₂O₃膜的厚度和氧化产物Mo₅Si₃均增加。并且,升高温度促进了Si和B的互扩散,加速了Mo₅Si₃和Mo₅SiB₂/MoB层的增长。在1300 ℃下,由于单峰结构的MoSi₂涂层拥有更多的晶界,使得含涂层的细晶合金相比含涂层的双峰结构合金表现出更多的氧化增重。     

Preparation and characterization of Ca-P coating on AZ31 magnesium alloy

A Ca-P coating consisting of biodegradableβ-tricalcium phosphate[β-TCP,β-Ca3(PO4)2]accepted for medical application was coated on a biodegradable AZ31 alloy by chemical deposition to improve the corrosion resistance.The good bonding strength of the coating is obtained.The results show that the corrosion potential of the Ca-P coated AZ31 alloy increases significantly,and MG63 cells show good adherence,proliferation and differentiation on the surface of the coated alloy.The Ca-P coating might be an effective way to improve the surface bioactivity of magnesium alloys.     

Biodegradation Behavior of Coated As-Extruded Mg–Sr Alloy in Simulated Body Fluid

As-extruded Mg–Sr alloy, a kind of promising biodegradable biomedical material, was coated using micro-arc oxidation and also using a phosphate conversion coating. The corrosion behaviors were investigated using Hanks' solution. The corrosion of the as-extruded Mg–Sr alloy became more serious with increasing immersion time; that is, the corrosion pits became more numerous, larger and deeper. The micro-arc oxidation coating and the phosphate conversion coating were effective in improving the corrosion resistance of the as-extruded Mg–Sr alloy. The micro-arc oxidation coating was much more effective. Moreover, the as-extruded Mg–Sr alloy and the coated as-extruded Mg–Sr alloy exhibited lower corrosion rates than the as-cast Mg–Sr alloy and the corresponding coated as-cast Mg–Sr alloy, indicating that the corrosion properties of the coated samples are dependent on their substrates. The finer microstructure of the substrate of the as-extruded condition corroded much slower. The corrosion resistance of the coated Mg–Sr alloy depended on the coating itself and on the microstructure of the substrate.     

Self‐healing properties of TiO2 particle–polymer composite coatings for protection of aluminum alloys against corrosion in seawater

TiO₂ particle–polymer composite coatings were applied to the surface of a 5083 aluminum alloy. After using a knife to create an artificial defect, polarization resistance was monitored in artificial seawater at a temperature of 30 °C. The polarization resistance of the specimen coated with the composite polymer containing 3 vol% TiO₂ particles increased significantly over time, suggesting that the composite coating had self‐healing properties. A carbon‐containing 2‐µm thick film was found on the coated aluminum substrate at the site of the artificial defect. The formation of the film was related to the dissolution of bisphenol A (BPA), which is a chemical precursor of the polymer coating that behaved as an inhibiting agent.     

激光熔覆纳米TiC增强AlCoCrFeNi高熵合金磨损及腐蚀性能研究

采用激光熔覆技术在 304 不锈钢表层制备了纳米 TiC 增强 AlCoCrFeNi 高熵合金涂层,利用扫描电镜、能谱仪、X 射线衍射仪等设备系统研究了涂层的组织形貌、相结构及元素分布;采用显微硬度计、摩擦磨损仪、超景深显微镜和电化学工作站等设备表征了涂层的硬度分布、磨损特性及耐腐蚀性能。结果表明,类球形纳米级 TiC 与棒状微米级 TiC 沉淀相均匀分布在涂层 bcc（B2）相基体中。添加 TiC 增强相后,AlCoCrFeNi 高熵合金涂层的硬度比未添加 TiC 涂层的硬度提升了 15%;表层磨损率及磨损后表面单位面积粗糙度（Sa）分别较 AlCoCrFeNi 高熵合金涂层降低了 42% 和 18%,涂层中 TiC 增强相的弥散强化作用是涂层硬度、耐磨性提升的主要原因。添加 TiC 的 AlCoCrFeNi 高熵合金涂层较未添加 TiC 涂层的自腐蚀电流降低了约1个数量级,TiC 增强相使涂层表面形成致密的钝化膜是其耐蚀性能好的主要原因。