微量RE和Al对Sn-9Zn焊料组织与性能的影响

采用正交试验研究了微量RE和Al对Sn-9Zn无铅焊料电导率、硬度、润湿性及微观组织的影响,并与传统锡铅焊料进行了对比。Sn-9Zn焊料的电性能及力学性能优于传统锡铅焊料,但润湿性较差。添加微量RE和Al可以显著提高Sn-9Zn合金铺展率、细化组织,且不降低焊料电导率和力学性能,最佳w(RE)和w(Al)分别为0.05%和0.10%,铺展率达到61.98%,与Sn-9Zn相比提高了13.40%,硬度为20.90HB,电导率为8.15×106S/m。     

STM32F103RE在语音便携式乳腺血氧检测仪中的应用

本文介绍了一种低功耗的ARM Cortex—M3微处理器STM32F103RE及其在语音便携式乳腺血氧检测仪中的应用,设计和分析了语音便携式乳腺血氧检测仪中的STM32F103RE系统、探头以及接口电路。     

Effect of Sm on the cyclic stability of La–Y–Ni-based alloys and their comparison with RE–Mg–Ni-based hydrogen storage alloy

The LaY₂Ni_9.7Mn_0.5Al_0.3 and LaSm_0.3Y_1.7Ni_9.7Mn_0.5Al_0.3 alloys have been synthesized to investigate the effect of Sm partial substitution for Y on the cyclic stability of A₂B₇-type La–Y–Ni-based alloys. Their cyclic properties were also compared with the A₂B₇-type (RE_0.85Mg_0.15)₂(NiAl)₇ (RE = Rare Earth) alloys. The gas-solid and electrochemical cycle lives were tested. The structural stability, pulverization, and oxidation/corrosion performances were studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), and electrochemical methods. The partial substitution of Sm for Y improves anti-corrosion and anti-pulverization performances, thereby increasing the cycle life of A₂B₇-type La–Y–Ni-based hydrogen storage alloys. The A₂B₇-type RE–Y–Ni-based alloys exhibit better crystal structure stability, but the gas-solid and electrochemical cyclic stability is worse than A₂B₇-type (RE_0.85Mg_0.15)₂(NiAl)₇ alloys due to easier pulverization of particles and the oxidation of Y elements.     

Phase composition and property evolution of (Yb1−xHox)2Si2O7 solid solution as environmental/thermal barrier coating candidates

RE disilicates are good candidates as environmental/thermal barrier coating for SiC_f/SiC composite in harsh gas turbine engines. We designed (Yb_1?xHo_x)₂Si₂O₇ solid solutions and studied mechanical properties, thermal properties, and water vapor resistance. Powders with different compositions were synthesized by pressureless sintering, and bulk samples were prepared by Spark Plasma Sintering (SPS). Polymorphic changes with temperature and composition of the solid solutions were examined. Through doping Ho into Yb₂Si₂O₇, water vapor corrosion resistance is significantly promoted, and thermal expansion coefficient is maintained close to that of Si-based ceramics. Compared with host disilicates, thermal conductivity of solid solutions are decreased, and mechanical properties, including Vickers hardness and fracture toughness, are increased. A two-phase domain is found at (Yb_1/2Ho_1/2)₂Si₂O₇, and the γ to δ phase transition of Ho₂Si₂O₇ is observed during SPS. Among all samples, γ-(Yb_1/3Ho_2/3)₂Si₂O₇ possesses superior high temperature stability, and excellent water vapor resistance, indicating its performance as environmental/thermal barrier coating.     

变质钨合金铸铁衬板的研究和应用

以钨渣铁合金为主要合金原料制造钨合金铸铁衬板,研究了稀土变质处理提高其使用寿命的可能性。结果表明,钨合金铸铁经适量稀土变质处理后,共晶碳化物由网状分布变成断网状分布,冲击韧性和耐磨性显著提高,变质钨合金铸铁用于制作混凝土搅拌机衬扳,使用安全、可靠,使用寿命与高铬铸铁和镍硬铸铁相当,成本降低50％～60％。     

稀土与热处理对高碳铬铸钢碳化物的形态及冲击韧性的影响

研究了稀土与热处理对高碳铬铸钢碳化物的形态及冲击韧性的影响。结果表明，稀土和热处理均能改善高碳铬碳钢碳化物的形态与分布，提高其冲击韧性，尤其稀土与热处理共同作用时，效果更显。     

基于自适应蒙特卡洛法的磁场辐射发射测量不确定度评定

针对测量不确定度评定中测量不确定度表示指南法（GUM）不适用于输入输出变量关系非线性或输出变量非正态分布的情况,提出采用自适应蒙特卡洛法（AMCM）评定25 Hz～100 kHz磁场辐射发射（RE101）测试的测量不确定度。首先阐述蒙特卡洛法（MCM）和AMCM评定测量不确定度的计算步骤,其次分别用AMCM和GUM法评定RE101测量不确定度,在相同的包含概率下比较两种方法的覆盖区间差值与数值允差,表明AMCM的评定结果可靠性更高,适用于RE101测量不确定度评定。AMCM可以推广到其他电磁兼容测试项目的不确定度评定中,将有效提高不确定度评定的可靠性。     

稀土La和Ce及超声处理对ZL201铝合金显微组织及抗拉强度的影响

本工作研究了稀土元素La和Ce的添加量及超声处理对铸态ZL201铝合金显微组织形貌、晶粒大小和抗拉强度的影响。结果表明:添加适量的稀土元素可有效抑制晶粒长大,进而细化枝晶和晶粒尺寸。添加稀土元素的ZL201-0.2%(质量分数,下同)La合金抗拉强度为207MPa,ZL201-0.6%Ce合金抗拉强度达到223MPa,分别比未添加稀土元素的ZL201合金提高了10.7%和19.3%。经超声处理后,ZL201-0.1%La合金抗拉强度达到247 MPa,比未经超声处理的ZL201-0.1%La合金提高了50.6%;ZL201-0.3%Ce合金抗拉强度达到226 MPa,比未经超声处理的提高了10.2%。