Effect of humidity and temperature on the adhesive strength of pressure sensitive adhesives

This paper reports the effect of humidity and temperature on the adhesive strength of a pressure sensitive adhesive (Flexbond 150) used to bond Mylar films. It has been found that, ill general, the adhesive strength decreases significantly with an increase in temperature. The effect of humidity on the bonding strength, however, was found to be process dependent. The sample preparation conditions, e.g., press weight for the bonding and the press time, are important in determining the humidity effect. The water sorption isotherm A 24°C for the adhesive was also determined. The amount of water sorbed by the adhesive at 95 percent relative pressure was found to be less than one weight percent.     

Structure and thermal properties of heat treated plasma sprayed ceria–yttria co-stabilized zirconia coatings

Thick plasma sprayed thermal barrier coatings are suitable for thermal and hot corrosion protection of metal components in land-based turbine and diesel engines. In this work, ceria–yttria co-stabilized zirconia coatings were deposited by atmospheric plasma spraying in a mixture of non-transformable tetragonal t′ and cubic c zirconia phases. Free-standing coatings were isothermally annealed at 1315 °C for different times and their crystal structure was studied by XRD. No phase decomposition occurred. Columnar grains grew in the molten splats with increasing annealing time according to a preferential direction and, after 50 h of heat treatment, they were partially replaced by equiaxed grains. Both in-plane and out-of-plane thermal expansion coefficients (CTEs) were measured from coating expansion during heating. The CTE was slightly sensitive to thermal exposure in out-of-plane direction, whereas it kept almost constant in plane direction. The specific heat capacity Cp of annealed coatings, measured by differential scanning calorimetry (DSC), decreased in comparison with as-sprayed coating, due to high-temperature sintering.     

欧洲与北美制造的烧结青铜含油轴承性能的比较

多孔性青铜含油轴承是全世界都在生产的，最早与最无处不用的现代粉末冶金产品。然而，各地区产品之间仍存在着明显差异。近期发布的粉末冶金材料的全球标准ISO5755，其中有2个描述轴承材料性能的数据表。其中列举的几项关键性轴承特性和MPIF标准35或相应的ASTM标准中列出的轴承性能有所不同。因此，MPIF标准委员会进行一项小型试验，对标准90％（质量分数）Cu-10％（质量分数）Sn轴承的关键特性进行了对比。这项研究的样品零件来自欧洲与北美的大批量生产厂家。数据证实孔隙度与径向压溃强度不同，这种差异是原料粉与制造工艺的微妙差异所致。最终用户应该了解这些差异，和确认IS05755中列举的特性能满足他们对轴承的要求。