Effect of TiO_2 content on properties of Al_2O_3 thermal barrier coatings by plasma spraying

Al2O3 thermal barrier coatings with different TiO2 contents were deposited on 6061 aluminum alloy by plasma spraying. The corrosion resistance, thermal insulation property and phase composition of these coatings were investigated. The results indicate that all the feedstock powders exhibit phase transformation during the spray process. With the increase of the TiO2 content in the powder, the corrosion resistance of the coating is enhanced but the thermal insulation property is decreased. This can be attributed to the higher thermal conductivity but lower melting point and brittleness of TiO2 than those of Al2O3, so it is easy for TiO2 to disperse in the brittle Al2O3 substrate during spraying, in which these dispersively distributed TiO2 play the role of hole sealing, releasing stress and reducing cracks.

激光重熔对等离子喷涂ZrO_2-20%Y_2O_3热障涂层隔热性能的影响

采用大气等离子喷涂(APS)技术在铝基体表面制备氧化锆(ZrO2-20%Y2O3,质量分数)热障涂层,并用脉冲激光对其进行重熔处理,研究了激光重熔对涂层组织形貌、物相转变和隔热性能的影响。研究结果表明激光的比能量对涂层的成型及性能有重要影响,过高的比能量会使涂层表面粗糙度增加,涂层成型变差。在选用合适的低比能量激光重熔条件下,扫描电镜观察结果表明经激光重熔可消除喷涂态涂层的孔隙和层状结构。对粉末和重熔前后的涂层进行了X射线衍射分析,结果表明喷涂及重熔过程中都没有发生相变;隔热试验结果表明重熔后涂层的隔热温度有所下降。

造渣剂对激光熔覆制备铁铝金属间化合物的影响

通过激光熔覆添加和不添加造渣剂的铁铝混合粉末在Q235钢基体上制备出铁铝金属间化合物熔覆层,研究了造渣剂对熔覆层的组织和性能的影响.结果表明,向熔覆粉末中添加造渣剂不仅可以显著细化熔覆层晶粒,还可以影响熔覆层的物相结构.当熔覆粉末中Fe,Al原子比例接近3:1时,所制备的熔覆层均由B2结构的FeAl相和DO3结构的Fe3Al组成,但添加造渣剂后所得熔覆层中含有较多DO3结构的Fe3Al.结果表明,添加造渣剂的熔覆层有着更高的显微硬度、更好的抗氧化性能和耐蚀性能.

椎旁肌间隙入路内固定治疗胸腰段椎体骨折

目的探讨经多裂肌及最长肌肌间隙入路(以下简称肌间隙入路)和传统后正中入路钉棒系统内固定治疗胸腰段椎体骨折临床疗效比较。方法回顾2006年8月至2010年3月经后路钉棒系统撑开复位内固定治疗56例无神经症状胸腰段椎体骨折患者,其中采用肌间隙入路30例,男17例,女13例,年龄30-60岁,平均40.7岁;传统椎旁肌剥离入路26例,男19例,女7例,年龄24-54岁,平均30.2岁。记录两组患者手术时间和出血量,测定两组患者术前术后胸腰段后凸畸形Cobb角,对相关临床数据进行统计学分析。结果所有患者均获得随访,术后随访时间18-24个月,平均19个月,肌间隙入路手术时间短,出血少,两组患者术前术后Cobb角差异有统计学意义,临床疗效相同。结论肌间隙入路钉棒系统内固定治疗无神经症状的胸腰段椎体骨折具有置钉方便、手术时间短,创伤小、出血少、并发症少、恢复快等优点,临床疗效满意。