Ni-Al-Cu粉末合金激光点火反应烧结的致密化研究

主要研究了激光点火反应烧结Ni—Al—CU系粉末材料的致密化机理。随体系中Cu含量的增多,大颗粒的Ni—Al—Cu粉末压坯在激光快速点火和烧结下实现了无压致密,最终产物并没有发生显著地改变。液相和被瓦解的固相小晶粒或颗粒的共同填充是导致最终致密的主要机理。     

镁合金化学镀Ni-W-P合金

将AZ91D镁合金无铬处理后,以硫酸镍和钨酸钠为主盐,柠檬酸钠和碳酸钠为复合络合剂,在碱性镀液中通过调整镀液组成,得到W含量较高的Ni-W-P合金镀层。此镀层中W及P的质量分数分别为4.50%和4.84%。通过孔隙率和极化曲线测量了此镀层的耐蚀性能,表明该镀层能够很好地提高AZ91D镁合金的耐蚀性。     

颗粒增强金属基复合材料的屈服行为

运用空间轴对称弹塑性有限元方法和混合律模型，给出了应力应变分配系数与复合材料的弹性模量，屈服强度以及切线模量之间的定量关系式，并由此提出了一种新的定义颗粒增强金属基复合材料比例极限和屈服行为的方法，进而研究了颗粒形状（球体，正圆柱体以及椭球体）和材料结构参数（颗粒体积分数和颗粒根间距）对颗粒增强金属基复合材料拉伸变形行为的影响。研究表明，通过研究应力应变分析系数及其二阶导数来确定复合材料屈服行为的方法不仅适用于短纤维增强金属基复合材料，而且也适用于颗粒增强金属基复合材料。该方法可以较好地反映出颗粒形状和材料结构参数对复合材料屈服行为的影响，预测的比例极限与已发表的实验结果吻合较好。     

面向产品制造的注塑模CAD／CAM的应用

提出了面向产品制造的注塑模CAD／CAM的设计方法,完成了面向产品整个制造周期的CAD建模,进行了CAD／CNC数据共享、调试及刀具轨迹的模拟研究。     

面向产品制造的注塑模CAD/CAM的应用

提出了面向产品制造的注塑模CAD/CAM的设计方法 ,完成了面向产品整个制造周期的CAD建模 ,进行了CAD/CNC数据共享、调试及刀具轨迹的模拟研究。     

Effect of substrate temperature on structural properties and photocatalytic activity of TiO2 thin films

Titanium dioxide （TiO2） films with anatase structure were prepared on quartz glass substrates by pulse laser ablating titanium （99.99%） target under oxygen pressure of 10 Pa at substrate temperature of 500-800 ℃. The structural properties of the films were characterized by X-ray difffactometry（XRD）, X-ray photoelectron spectroscopy（XPS） and field emission scan electron microscopy（FESEM）. The results show that, as the substrate temperature is increased from 600 ℃ to 800 ℃, the anatase structure of the films changes from random growth to （211）-oriented growth. The absorption edge tested by UV-Vis Spectrometer has a blue shift. The photocatalytic activity of the films was tested on the degradation of methyl orange. It is found that the film with random growth structure exhibits better photo-degradation efficiency than that with （211）-oriented growth structure.     

短纤维增强金属基复合材料的热残余应力及其对拉伸和压缩载荷下应力分布的影响

运用空间轴对称有限元方法,研究了短纤维增强金属基复合材料热残余应力的分布及其对拉伸和压缩载荷下应力分布的影响.研究表明,在拉伸和压缩载荷下,热残余应力可导致不对称的应力分布;热残余应力降低拉伸时的应力传递,加强压缩时的应力传递.     

Effect of grain size on corrosion behavior of electrodeposited bulk nanocrystalline Ni

Nanocrystalline (NC) and coarse-grained Ni with different grain sizes (from 16 nm to 2 μm) were fabricated by direct current electrodeposition. Effect of grain size on the electrochemical corrosion behavior of these Ni deposits in different corrosion media was characterized by using potentiodynamic polarization test, electrochemical impedance spectroscopy (EIS), X-ray photoelectron spectroscopy (XPS) and immersion corrosion test. Results show that in the NaOH or NaCl solution, the NC Ni exhibits improved corrosion resistance with the decrease of grain size. But in H2SO4 solution, the higher grain boundary density accelerates corrosion due to no passive process and the corrosion resistance of NC Ni decreases with refining grain size. The distinct experimental results of NC Ni in corrosion behavior can be reasonably explained by the positive or negative effect of high-density grain boundaries in different corrosion media.