喷涂和刷涂对预涂卷材修补再涂装的试验研究

预涂卷材在加工及使用过程中涂层局部剥落、损坏是不可避免的,因此其维护与再涂装是非常必要的。通过对预涂卷材表面进行简单的机械去除浮锈和有机试剂擦拭除油的前处理,采用7种常用涂料对已被破坏的卷材表面喷涂和刷涂再涂装,测试了2种涂装方法下漆膜性能,分析并得到了这7种涂料在预涂卷材再涂装时的可行性和适用场合,所得实验结果对实际应用具有一定的参考价值。     

Effect of recoating slurry compositions on the microstructure and properties of SiC reticulated porous ceramics

Silicon carbide reticulated porous ceramics (SiC RPCs) were fabricated by polymer sponge replica technique, followed by recoating with SiC slurries of two different sintering additives of MgO–Al₂O₃–SiO₂ (Slurry 1) and polycarbosilane (Slurry 2). The sintering temperature of SiC RPCs recoated with Slurry 2 was 1100 °C, which was 200 °C lower than that for one recoated with Slurry 1. The prepared SiC RPCs exhibited homogeneous microstructure and contained pores with different sizes which was entrapped in the strut of SiC RPCs, small pores with diameter lower than 4 μm and large pores with diameter higher than 10 μm. Bending strength of SiC RPCs recoated with Slurry 1 was two times higher than that for the non-recoated samples, which was 1.88 MPa and was a little higher than that for one recoated with slurry 2. At the same time, high thermal shock resistance and high refractoriness were achieved for SiC RPCs recoated with Slurry 2.     

高分辨率激光快速成形系统研究与开发

开发了一种新型激光快速成形系统。利用该系统可制作尺寸范围为65 mm×65 mm×150mm的制件原型。 该系统由He-Cd单模激光器、小光斑扫描系统、新型树脂涂层系统及控制系统组成。由扩束镜、高精度扫描振镜 及f-θ透镜构成扫描系统,扫描面上的激光光斑直径达到0.012 mm。由蠕动泵、高精度工作台、树脂槽及刮刀组 成新型精密树脂涂层系统,树脂涂层厚度达到0.02 mm。利用该系统制作了具有微流道的滴灌器件及其他微型零 件的原型。     

动态优化刮刀速度的新型涂层工艺

为提高活塞式无扰动涂层工艺的涂层质量,针对高分辨率激光快速成形系统涂层工艺中存在的涂层厚度随制件高度增加而变厚的问题,提出在制作过程中动态优化刮刀速度的涂层方法。研究刮刀速度、制件高度对涂层厚度的影响。采用面响应法,建立涂层厚度误差关于制件高度及刮刀速度的数学模型。根据该模型,在制作过程中随制件高度的变化,动态优化刮刀速度,实现涂层厚度均匀化。验证试验结果表明：与普通涂层工艺相比,新型涂层工艺将涂层厚度偏差由27 μm降为6.9 μm,解决了涂层厚度随制件高度增加而变厚的问题,实现涂层厚度的均匀化,提高堆积方向的制作精度。该涂层工艺也可应用于普通光固化激光快速成形系统中,解决制作陷阱结构时涂层厚度随制件高度变厚问题,因此该工艺对于光固化快速成形技术中提高堆积方向制作精度具有重要意义。