The corrosion behaviors of low-pressure sand cast Mg-10Gd-3Y-0.5Zr (wt.%) alloys in as-cast, solution treated (T4) and aged (T6) conditions were studied by means of immersion test and electrochemical measurements in 5wt.% NaCl solution saturated with Mg(OH)2. It was observed that the corrosion rate in the T4 condition was lower than that of the as-cast and T6 conditions by both sand casting and permanent mold casting with the same order of as-cast>T6>T4; while the corrosion resistance of the permanent mold casting is superior to the sand casting. The morphologies of the corrosion products are similar porous structures consisting of tiny erect flakes perpendicular to the corroded surface of the alloy, irrespective of the heat treatment conditions. Especially, the corrosion film in T4 condition is more compact than that in the other two conditions. In addition, the severer corrosion happening to the as-cast condition is correlated with the galvanic corrosion between the matrix and the eutectic compounds; while improved corrosion resistance for the T4 and T6 conditions is ascribed to the dissolution of the secondary eutectic compounds. The measured corrosion current densities of Mg-10Gd-3Y-0.5Zr alloys in as-cast, T4, and T6 conditions are 36 μA·cm-2, 10 μA·cm-2, and 33 μA·cm-2, respectively. The proposed equivalent circuit [Rs(CPE1(Rt(RfCPE2))] by Zview software matches well with the tested electrochemical impedance spectra (EIS) data.

The eccentric wear failure of some automotive engine exhaust valve guide were analyzed.The chemical composition,structure,hardness and density of failure valve guide and normal valve guide were analyzed.The results show that the low carbon content of the failure valve guide causes the low relative content ofpearlite,which can result in the decrease of hardness and the low hardness cannot reach the design requirement,which is the main reason for the eccentric wear failure of valve guide.Some relevant improvement measures against the failure reason for the valve guide were proposed.

介绍了金属丝编织防波套、金属复合带、半导电高分子材料、电化学镀屏蔽膜和导电涂料等电缆屏蔽材料的组成、结构、制造工艺、特点、应用及发展现状,有助于电缆制造厂商和用户根据实际工作条件,合理选择屏蔽材料及制造方法.

Iron-based P/M valve seat with good mechanical properties was prepared by sintering,infiltration and heat treatment.Effects of different processes on porosity,density,microstructure and mechanical properties of the P/M valve seat were investigated,and the preferable process of the valve seat was determined.The results show that the pore shape becomes spheroid,the number and size of pores reduce,and the density of the valve seat is improved significantly by infiltration process or increasing the sintering temperature.The optimum process is infiltration and sintering at 1150 ℃ for 2 h with adding 14％ ～ 15％ thin copper(weight ratio),and then tempering at 620 ℃.

Ni60 and Ni60 /WC coatings were prepared by plasma cladding method on substrate of 45 # steel. High-temperature antioxidation properties of the composite coatings were investigated by means of SEM,EDS and XRD. The results showed that the oxidation rate was mainly controlled by O2-inner-diffusing in the initial oxidation stage while in the later stage the dominated diffusion was Cr3 +. The oxidation films of coatings were composed of SiO2and Cr2O3,while a spot of NiCr2O4spinel oxide could also be detected on the surface of Ni60 + WC coatings. The antioxidation properties of the composite coatings were codetermined by both the chemical composition and phase structure. Adding of the WC powder could improve the high-temperature antioxidation properties of the coatings.

将超声波引入Co-Ni-P合金的化学镀中,讨论了超声波功率、超声波频率、主盐、还原剂、配位剂、温度及pH值对化学镀Co-Ni-P合金沉积速率的影响。超声波的介入提高了沉积速率,功率较大时镀液的稳定性下降。通过分析工艺,得出了超声波下化学镀Co-Ni-P合金的最佳工艺。

采用2种常用的烧结温度制备Fe-Cu-C系气门导管,然后对其显微组织、密度、硬度和压溃强度进行测试.结果表明:相比于1 120℃烧结的试样,1 150℃烧结试样在高温区的脱碳更严重,珠光体数量减少,硬度降低,且高温会加速Cu的扩散,使孔隙增加,降低试样致密度.从组织性能、生产成本考虑,烧结温度以1 120℃为宜.

Compared with other surface modification technologies,induction melting technology has many unique advantages and is more widely used.The principle of induction melting was introduced briefly,with the focus on its development,technological process,influencing factors and control methods.The development trend of induction melting technology was prospected.

Silane treatment is a surface treatment technology promising to replace chromating process,because it has characteristics of simple process,low pollution,high-performance,etc.The mechanism,process and modification progress of silane treatment are summarized.

Electrodeposition conditions of Fe-Ni-S,Fe-Ni-Cr,Fe-Ni-W,Fe-Co-Ni and Fe-P-B amorphous ternary Fe-based alloy magnetic films were reviewed in this paper.Corrosion resistance,wear resistance,thermal stability and magnetic properties of the Fe-based alloy magnetic films were also introduced.Finally,future direction of the Fe-based alloy magnetic films was put forward.

Aluminum alloy was first oxidized anodically by boric acid-sulfuric acid,and then sealed by Ce(NO3)3-KMnO4 solution.The optimum content of KMnO4 was determined by the mass changing of sealed and unsealed samples,dropping test,weight loss test in phosphorus acid-chromic acid without nitric acid predipping.The surface morphology and the corrosion resistance of oxidation films before and after sealing were observed and measured.Results showed that an even,compact passive film was obtained on the oxidation film,and the corrosion resistance of samples was improved after RE sealing.

The optimum process parameters of silane film on aluminum alloy were obtained by orthogonal experiment.The silane film was prepared and its corrosion resistance was evaluated by dropping corrosion test.Results indicated that the hydrolysis and condensation reaction of silane solution were mainly affected by hydrolysis temperature,silane concentration,alcohol-water ratio and pH value.The surface morphology of silane films was analyzed,and the corrosion resistance of silane films was determined.The silane film was uniform,compact and had a better corrosion resistance than chromate conversion coating.

Although magnesium alloy has a lot of advantages,its development and application were limited because of its lower corrosion resistance.In this paper,the forms of corrosion and conversion film used on magnesium alloy surface were reviewed.And the uniform and localized corrosion,and the present status,processing condition,corrosion mechanism and developmental trend of chemical conversion,anodic oxidation,organic compound conversion film were mainly discussed.Finally,the developmental tendency of protection techniques on magnesium alloy is prospected.

The invention discloses a rare-earth modified tin alloy for continuous hot-dip coating of a copper wire and a copper-coated metal composite wire, and a manufacturing method thereof. The rare-earth modified tin alloy is prepared from the following raw materials in percentage by weight: 0.5-2.0% of In, 0.1-0.4% of Bi, 0.05-0.08% of P, 0.1-1.0% of rare earth and the balance of Sn, wherein the rare earth is selected from Ce-rich mixed rare earth formed by La, Y or Ce and La. In the vacuum condition, intermediate alloy of Sn-P or Sn-RE is prepared, and the uniformity, fluidity, wet spreadability, heat stability, oxidation resistance and the like of tin bath chemical composition can be improved by the modification function of rare-earth element which does not contain single Ce or mixed rare earth; and the surface of the tinned copper wire (or copper-coated metal wire) has excellent weldability and oxidation resistance.

As a fine surface treatment technology,electroless copper-plating has been widely used in electronics,mechanical,aerospace industries,etc.The research on the mechanism and new processes of electroless copper-plating is a hot subject in surface metallization of electronic products.The mechanism and the applications of electroless copper-plating technique are described.Its main problems faced and future research directions are presented.

Aluminum alloy anodic oxidation technology can greatly improve hardness,corrosion resistance,wear resistance of the substrate surface.But the usable life of aluminum alloy parts the anodic oxidation film without sealed is not long.The purpose of sealing is to improve wear resistance,corrosion resistance′ hardness and ability of anticontamination of the surface.Sealing is a very important technology.Some conventional and new sealing treatments for anodic oxidation film of aluminum alloys were summarized.

Effects of copper sulfate concentration,complexing agent concentration ratio,formaldehyde concentration,rare earth content and temperature on copper deposition rate,coating microstructure of electroless copper plating on ceramic were discussed.Results showed that with the increase in copper sulfate concentration and temperature and decrease in complexing agent ratio,the Cu deposition rate was increased but bath stability decreased;with increasing formaldehyde concentration and rare earth content,the Cu deposition rate was increased at first and then decreased.By adding rare earth Ce salt,copper particles got refined and copper depositon became even,especially when cerium sulfate content was 0.8g/L,copper coating became more level,finer and less pores.

The optimum electric voltage,time,temperature of sulfuric acid-boric acid anodic oxidation electrolyte for aluminum alloy were obtained by orthogonal experiment,and then different amounts of cerous sulfate were added in the optimum electrolyte.The corrosion resistance of aluminum alloy anodizing film obtained from these electrolytes was determined by salt spray and immersion tests and polarization curve measurement.The content of cerous sulfate was optimized.