金属针布钢丝球化退火的质量控制

对金属针布生产与使用特点进行分析 ,认为最佳的钢丝球化退火工艺是金属针布尺寸精度、基体组织、最终淬火质量的保证。对于 5 7B针布钢丝 ,采用低于Ac12 0～ 4 0℃的球化退火温度可使球化级数达到 3～ 3.5级 ,硬度达到 170～ 190HV ,满足高速轧制要求。金属针布钢丝球化退火质量的控制与管理 ,对金属针布稳定化生产和产品质量的一致性起重要的作用。     

10B21低碳合金钢线材正交试验优化球化退火工艺

介绍低碳合金钢10B21球化退火工艺的优化。采用正交试验确定加热时间、加热温度、保温时间、冷却速度对球化退火工艺的影响,由此获得10B21球化退火的最佳工艺。试验结果可知:最佳球化退火工艺为加热时间6h,保温温度720℃,保温时间6 h,冷却速度20℃/h;在球化退火过程中,保温温度和冷却速度为退火工艺的主要影响因素,必须严格按工艺控制保温温度和冷却速度。引入正交试验设计方法可有效地减少试验次数,对生产和实践具有一定的指导作用。     

15CrMo钢的高温时效性能的变化规律及计算模型

根据现有标准DL/T 787-2001提供的数据分析了随温度和球化等级的改变,15CrMo钢的碳化物相中钼元素含量、抗拉强度、屈服强度、伸长率、断面收缩率以及硬度的变化规律,同时建立了相关计算模型,并且预测出球化等级为1.5,2.5,3.5和4.5级所对应的性能参数值.此外还分别给出了依据常温抗拉强度、屈服强度、布氏硬...     

等离子合成与雾化制粉技术及其应用

等离子体做为一种极端参数技术在粉体材料的球化处理与合成制备方面的研究和应用日益引起人们的关注。本文概述了等离子技术的主要特点及应用领域,综述了国内外有关射频等离子体对不同金属粉末、陶瓷粉末的球化处理及纳米粉末的合成方面的研究成果;介绍了北京科技大学在射频等离子体粉体处理系统开发、制备球形钨粉和钛粉方面的研究成果,在此基础上对等离子体粉体球化处理技术的应用前景进行了展望。     

Radio frequency plasma processing to produce chromium sputter targets

Production of thick chromium layers on copper substrates used for sputter targets provides a number of technological challenges. These challenges were addressed using radio frequency (RF) plasma spray technology. The efforts were focused on several objectives. The coatings should be as dense as possible with residual stresses low enough to avoid strong substrate bending and to prevent adhesive and/or cohesive failure of the coating. In addition, the deposition efficiency should be maximized. Different parameters were varied to find the optimum spraying conditions. Two different powder grain sizes, −90+45 μm and −63+20 μm, were used. First, a spheroidization study was performed to select the most suitable chamber pressure, the optimum plasma power, and a reasonable range of the powder feed rate. During deposition of the coatings, the powder feed rate, the spray distance, the substrate roughness, and the substrate cooling mode were optimized. The substrates were noncooled, gas cooled, or directly water cooled, respectively. The water-cooled samples showed no substrate bending; however, the thermal stresses occurring were strong enough to cause coating failure in adhesion or cohesion. Noncooled samples showed the best adhesion properties, while substrate bending could be kept within acceptable limits.     

Investigation of the processes of refining of ceramic articles in a plasma flow

Results of investigations of the process of dissipation of polydisperse particles in low-temperature plasma flow with the formation of ultrafine, including nanosized, particles are presented. A special method is proposed that can be used for producing polydisperse powders, including ultrafine and nanosized powders, with spherical particles and the amorphous, crystalline, or amorphous, crystalline structure.     

锅炉对流过热器爆管原因分析

通过现场观察过热器管子爆口特征及管壁吹损痕迹,分析确认过热器受热面泄漏后管子相互损坏关系及首爆口.经对管子取样试验数据分析,首爆口处管壁存在以AI元素为主要成分的异种金属物质,影响了管子的使用性能,长期运行后导致管子发生爆破.同时,管子存在一定程度的过热现象,加速了管材性能的劣化.     

多分散结构团聚体烧结的数值模拟

高温环境下团聚体颗粒的烧结现象决定了颗粒表面积、内部非均匀结构等。现有数值模拟方法中一般认为团聚体由若干尺度相同的一次粒子组成,不符合实验测量结果。该文考虑团聚体内一次粒子的多分散性,建立一次粒子质量平衡和数目平衡关系,描述烧结过程团聚体内一次粒子尺度分布函数的演变。对气相法制备TiO2纳米颗粒的烧结定制过程进行数值模拟,模拟结果与实验结果吻合较好,且考虑团聚体内一次粒子多分散分布的模型结果比考虑团聚体内一次粒子单分散分布的模型结果更精确。所建立的描述团聚体烧结过程的多分散模型可适用于多尺度模拟、颗粒群平衡模拟–Monte Carlo方法、多相流模拟的欧拉–拉氏模型等。     

汽车右下悬臂件的断裂分析

对进口飞鹰牌轿车右下悬臂件的断裂问题进行了宏观分析,确定了其断裂原因。