纳米Al203颗粒增强NiCoCrAIY合金激光熔覆涂层热腐蚀性能的研究

采用压片预置式激光熔覆工艺，添加适量Al2O3纳米陶瓷复合粉体，采用NiCoCrAlY合金粉末在GH4037合金表面激光熔覆制备了纳米Al2O3颗粒增强NiCoCrAlY合金涂层，分析了熔覆层显微组织，测定了熔覆涂层在1000℃时的热腐蚀动力学曲线，并对涂层进行了1000℃高温熔盐热腐蚀性能试验。结果表明，添加适量纳米Al2O3颗粒对NiCoCrAlY合金激光熔覆层组织具有明显的细化作用，对Cr20。膜在硫酸盐作用下的碱性溶解有一定的抑制作用，熔覆层的抗高温热腐蚀性能显著提高。但要得到最佳效果，纳米Al2O3颗粒的添加量存在一个合适值。

纳米Al_2O_3弥散强化复合涂层的制备及耐磨性研究

将纳米Al2 O3与Ni基自熔性合金F10 2的复合粉末用氧乙炔焰热喷焊工艺制备复合涂层 ,研究了纳米Al2 O3的加入量对组织和耐磨性的影响。结果表明 ,当纳米Al2 O3质量分数为 0 .2 5 %时 ,涂层的耐磨性最好 ,与 2 5 %WC复合涂层的耐磨性相当。

Experimental and Theoretical Studies of CO2 Absorption Enhancement by Nano-Al203 and Carbon Nanotube Particles

The influence of nano-particles on CO2 absorption was studied experimentally in a stirred thermostatic reactor. Nano-A1203 and carbon nanotube （CNT） particles which showed different hydrophobic properties were chosen for the investigation. The experimental results were compared with that of micron-size activated carbon （AC） and Al2O3 particles. From the results, no enhancement by micron-size A1203 was found, and with the increase of A1203 concentration, the enhancement factor decreased. However, nano-Al203 showed a weak enlaancement tor me COz absorption. AC and CNT particles all intensified the gas-liquid mass transfer effectively, yet the trend of the enhancement factor with stirring speed for the two particles was different. With increasing stirring speed, the enhancement factor of AC particles was decreased, wl＇iereas in CNT suspensions it was increased. The experimental phenomena demonstrated a difference in enhancement mechanism for different size particles. For nano-particles, besides the influence of adsorbability and hydrophobicity, the micro-convection caused by Brownian motion should be also taken into account. Considering the micro-convection effect, a theoretical model was developed to shed light on the absorption enhancement bv nano-oarticles.