汽车发动机散热器的发展趋势及其对铜材的要求

本文叙述了汽车发动机散热器的发展过程 ,对比了铜铝及其散热器的优缺点。指出新型铜钎焊式散热器具有重量轻、成本低、耐震、耐蚀、耐疲劳等优点 ,是汽车工业最好的散热器。

Effect of ball peening of substrate on microstructure, phase evolution and properties of electrophoretically deposited YSZ/(Ni,Al) composite coatings

YSZ/（Ni, Al） composite coatings were deposited on Inconel600 superalloy with ball peening （BP） and without （non BP）treatment using the electrophoretic deposition （EPD） technique, followed by vacuum sintering method. The structures and phaseevolution of the coatings were studied with X-ray diffraction （XRD）, scanning electron microscopy （SEM） and energy dispersivespectrometry （EDS）. The relation between microstructures and properties of the BPs-coated samples was discussed. The results showthat the adhesion strength and gain mass of the BPs-coated samples with isothermal oxidation at 1100℃ for 100 h are 3.3 N and0.00817 mg/cm^2, respectively, while those of the non-BPs-coated sample are 2.6 N and 0.00559 mg/cm^2, respectively. The EDSmapping analysis indicates that an obvious outward diffusion of Cr from the substrate to BPs coated samples occurs after isothermaloxidation. The BPs-coated sample shows the superior adhesion and oxidation resistance compared with non-BPs-coated samples.

Effects of Al and Ni doping on oxidation and corrosion resistance of electrophoretic deposited YSZ coatings

Yttria-stablized zirconia(YSZ)/(Ni,Al)coatings were deposited on Inconel600alloy substrate by the electrophoreticdeposition combined with vacuum sintering technique.The effects of isothermal oxidation at1100°C on the composition of thecoatings and the crack healing were investigated,and the corrosion resistance of the coatings in3.5%NaCl(mass fraction)solutionwas also studied.The results showed that the cracks on the coating gradually healed up with the increase of the isothermal oxidationtime.During isothermal oxidation process,the coating composed of Ni3Al was transformed toα-Al2O3particulates.Theα-Al2O3particulates can seal the defects such as pores and cracks,and meanwhile prevent the oxygen diffusion into the coatings.Thepolarization curves and EIS results indicated that the coatings oxidized for40h had a more positive corrosion potential,higherbreakdown potential,higher impedance module at low frequency and much lower corrosion current density compared with YSZcoated and uncoated Inconel600alloys.

Biodegradation behavior of polymethyl methacrylate−bioactive glass 45S5 composite coated magnesium in simulated body fluid

The biodegradation behavior of Mg,coated by polymethyl methacrylate as well as polymethyl methacrylate(PMMA)−bioactive glass(BG)composite was investigated.Electrophoretic deposition and dip coating techniques were adopted to prepare composite coating using a suspension of different percentages of the above two chemical materials.The deposited coatings were characterized using SEM,EDS,FTIR,and water contact angle measurements.Biodegradation behavior study of the coated Mg was performed using linear polarization,impedance spectroscopy,and immersion tests in simulated body fluid.The compact and homogeneous composite coating was developed as evidenced by electron microscopy results.The water contact angle measurement showed a 44°increase in the contact angle of the composite coated Mg compared to the uncoated one.The composite coating was covered by a bone-like hydroxyapatite layer after 336 h,indicating that the coating has an excellent in vitro bioactivity.The electrochemical testing results confirmed a significant reduction,96.9%,in the biodegradation rate of Mg coated with the composite prepared from 45 g/L PMMA+3.5 g/L 45S5 GB suspension compared to that of the uncoated one.Therefore,the composite coated Mg can be proposed as a promising material for biodegradable implant application.

真空助力器电泳漆工艺

介绍了电泳漆成膜机理。针对电泳漆后真空助力器的双重金属重合紧密处,出现白色堆积物的问题,改进了工艺。在除油、除锈、磁化后,电泳施工前于150℃烘烤30min,然后清理白色物质,进行彻底水洗后进行电泳漆工序,漆液浓度8％～12％,pH值控制在7.5～8.5之间,电压恒定在40±2V,电泳时间1.5～2min。