Influence of the composition of bronze-ferrochromium composites on their tribotechnical characteristics

Conclusions A bronze-5% ferrochromium composite material possesses the optimum tribotechnical characteristics in friction with lubrication, P=7 MPa, and v=1 m/sec. With an increase in ferrochromium content in the 0–10% range the hard inclusions hinder plastic deformation of the matrix. As the result there is a reduction in the capacity of the surface layers to distribute deformation under the action of contact loads in friction, that is, to run in to the abradent. Simultaneously, with an increase in ferrochromium content in the composite, the load in rubbing is absorbed to an increasing degree by the hard inclusions. With a ferrochromium content up to 5% the optimum combination of plasticity of the material and the capacity of the hard inclusions to absorb the load in rubbing is provided.Translated from Poroshkovaya Metallurgiya, No. 9(285), pp. 90–94, September, 1986.     

Effect of heat treatment on the strength and tribotechnical properties of material of LNKhB grade

Conclusions The Nichrome alloy was alloyed with niobium to produce the materials of the LNKhB7 and LNKhB8 grades with a heterogeneous structure which consist of an alloyed solid solution and nickel and a high-hardness phase, i.e., molybdenum carbide. Heat treatment (normalizing, aging) greatly hardens the material as a result of the formation of the high-hardness phase (Ni₃Al).The materials hardened with the high-hardness molybdenum carbide and the phase have high and stable strength properties in the temperature range 20–700°C (800°C); at temperatures higher than the temperature of hardening heat treatment the strength properties of the materials rapidly decrease.Alloying the grade LNKhB materials with niobium greatly improves the tribotechnical characteristics as a result of the formation of a surface film in the form of complex compounds on the friction surfaces.Translated from Poroshkovaya Metallurgiya, No. 7(283), pp. 74–77, July, 1986.     

高级刀剪材料的优化配料与成分控制

针对刀剪材料生产工艺,利用线性规划单纯形开发了配料模型,同时开发了LF精炼过程成份微调模型,用VB6.0和Access数据库编程实现.模型应用于生产实践,实现了配料成本的最优控制及窄成份控制,解决了实际生产中由于原材料来源广泛,造成的成份波动问题.计算结果与实际生产数据相比,基本一致,可用于实际生产.     

P型CuAlO2半导体陶瓷的烧结研究

性能良好的陶瓷靶材是溅射法制备薄膜的先决条件.本文以纳米级Al2O3粉体和微米级Cu2O粉体为原料通过烧结的方法制备了P型透明导电氧化物陶瓷CuAlO2.以X射线衍射和SEM分析的方法研究了烧结温度对反应进行的影响,并在合适的温度区间里得到了具有较好P型半导体性能的陶瓷,其迁移率达到27 cm2·V-1·s-1.以它作为靶材通过真空溅射得到了迁移率为2.1 cm2·V-1·s-1的P型透明半导体薄膜.     

热压烧结制备BN陶瓷复合材料的研究进展

介绍了利用热压烧结制备h-BN复合陶瓷的工艺过程和致密化过程,分析了Al N/BN、Si3N4/BN和SiC/BN复合陶瓷在力学性能、耐热性能、加工性能和介电性能方面的影响因素,最后对BN复合陶瓷的未来发展趋势进行了展望。     

高铝质陶瓷蓄热材料的研究开发

按蓄热式热交换器使用性能的要求和高铝质耐火材料的特殊性能和优点，选择适当的原料配方、特殊的成型和烧结工艺，研制开发出性能较为优越的陶瓷球蓄热材料。     

Determination of crash‐relevant material parameters by dynamic tensile tests

The mechanical properties of eight different steels, representing the wide range of steels for automotive application, are determined by accomplishing high speed tensile tests using flat sheet specimens. The steels chosen for investigations are deep drawing grade DC04, high strength steel ZStE340, three dual phase steels with strengths of 600, 800 and 1000 MPa, a TRIP steel and two austenitic stainless steels 1.4301 and 1.4318. Tests are carried out at five different strain rates within the range of 5‐10^?3 and 200 s^?1, all at room temperature. The results show different strain rate sensitivities according to the different grades of steel. The TRIP steel and both stainless steels show a great potential for energy consumption, when tested at high strain rates.     

Physicochemical evaluation of the compatibility of materials in tribotechnical pairs

Translated from Poroshkovaya Metallurgiya, No. 2(314), pp. 65–71, February, 1989.     

陶瓷外壳钎焊的工艺优化

陶瓷DIP外壳需要使用AgCu28钎料将4J42合金引线框架与陶瓷基板的焊区钎焊在一起,焊后易出现钎料在引线框架上流淌的问题,影响产品的质量.这些问题与钎焊工艺条件不当有关.本文在现场和实验室条件下系统研究了钎焊最高温度、保温时间和钎料用量等对陶瓷外壳钎料流淌的影响,发现钎料的流淌主要与在熔点以上温度停留的时间有关,并提出在下面三种工艺条件下可以获得较好的钎焊质量:先在700℃保温5min,然后在800℃保温4min,冷却;直接推到900℃高温区保温10min,再推到冷却区;以4min一舟,连续推舟通过810℃高温区或调整带式炉带速使外壳在熔点以上温度停留时间不超过5min.     

Optimization of rotatory tests in electronystagmography

The paper discusses optimization of rotatory tests as related to the classification of electronystagmograms. It presents criteria of the efficiency of the action on the vestibular analyzer taking into account statistical properties of different classes of electronystagmograms. The paper shows that the methods of variation statistics should be used to determine the category of action. The method described has been applied to identify an optimal action in the case of electronystagmograms of two classes (normal and pathology of a certain type). An action described as a sequence of delta-impulses of an angular acceleration has been obtained. A higher efficiency of the optimal action on the vestibular analyzer has been shown on the basis of a comparative study.     

微通道反应器内纳米头孢呋辛酯制备工艺优化

在Y型微通道反应器中,采用反溶剂沉淀法制备头孢呋辛酯纳米颗粒.通过正交实验,系统研究药物溶液质量浓度、沉淀温度、溶剂流量和反溶剂流量等因素对产物粒径的影响.得到的适宜制备工艺条件为:药物溶液质量浓度0.08g/mL、沉淀温度5℃、溶剂流量3mL/min.以及反溶剂流量80mL/min,制备出了粒径为260～340nm,且粒径分布窄的纳米颗粒.实验还进一步利用扫描电镜、X射线衍射、红外光谱分析和体外溶出实验对原料药及产品性质进行表征,结果表明:微粉化产品为无定形,溶出度明显优于原料药.     

超声空化对陶瓷刀具材料晶粒生长的影响

为了研究超声无压烧结陶瓷刀具材料时超声空化对晶粒生长的影响,分析了气孔在熔融金属中发生超声空化的条件,建立了含有空化泡的晶粒模型,讨论了超声空化对晶粒的作用,并采用蒙特卡罗法模拟了未施加和施加超声下的晶粒生长过程,研究了超声空化对晶粒生长过程的影响。结果表明:当空化泡的半径介于1 μm～2 μm时,超声波的声压阈值为8.02×106 Pa,频率阈值为2.00×106 Hz;超声空化可增大晶格振动频率和振动能量,阻碍晶粒生长,起到细化晶粒和减小孔洞的作用。     

切削不同铸铁材料的PCBN超硬材料刀具磨损研究现状

基于聚晶立方氮化硼(PCBN)超硬材料刀具的高硬度、良好的耐磨性及化学稳定性,其在汽车制造领域的应用变得越来越广泛。对国内外学者们使用PCBN超硬材料刀具加工灰铸铁、球墨铸铁和蠕墨铸铁的研究现状进行总结分析,主要从刀具材料、工艺参数、工件材料、切削环境及加工方式等几个方面对PCBN超硬材料刀具切削加工3种铸铁时的磨损机制进行讨论,最后总结了切削不同种类铸铁材料时刀具的磨损情况。     

Stand tests of cermet packing material UMB-4S

Conclusions Cermet packing inserts UMB-4S satisfactorily underwent special high-temperature long-time tests in equipment of the MA. The chemical composition, structure, and strength properties of the inserts after long-time testing changed negligibly, which predetermines the possibility of their use in equipment operating 1000 and more hours.The new packing material has higher performance properties than the batch-produced S-137 and can be recommended to replace it in equipment of the MA.     

包覆浇铸和热轧工艺制备Q235/CrWMn刀具材料

通过包覆浇铸+热轧变形工艺,制备了Q235/CrWMn钢复合刀具材料,并用扫描电子显微镜(SEM)和维氏硬度仪分析了复合材料的界面组织、成分和性能的变化规律.实验结果表明,通过真空冶炼浇铸以及变形量超过90%的热轧工艺,可以实现两种组元金属材料之间的冶金结合,其中Cr、W等元素的过渡层宽度仅为10～40μm.随后的热处理研究发现,复合材料在830±5℃保温后空冷或者油淬时,Q235一侧为珠光体+铁素体组织,CrWMn一侧为马氏体组织,其硬度可达600～750HV,使复合刀具材料同时具有较好的韧性和强度.