制造高密度零件的一种新工艺

介绍一种制造零件的粉末冶金新工艺,制造的零件性能可能相当于或好于球墨铸铁,密度可达7.55g/cm3。这一工艺正处于初期研发阶段,它实质上是一种首创性技术,在很大程度上既不是依靠高压力压制,也不是利用高温烧结。这一工艺有可能用于经济地生产大型零件,因为所需生坯密度低于6.8g/cm3,典型工艺温度为1175℃。本文将详细介绍当前对该工艺与技术依据的了解。     

Penetration of resin‐based materials into initial erosion lesion: A confocal microscopic study

The application of resin‐based materials is an alternative of treatment for eroded lesions. Nevertheless, there are no studies about the penetration of these materials into eroded lesion, which might affect its adhesion. Therefore, this study evaluated the penetration of four resin‐based materials, with and without enamel etching. By using an in vitro protocol, types of treatment were studied at five levels (AdheSE^®, Tetric N‐Bond^®, Single Bond 2^®, Helioseal Clear^®, Icon^®) and types of enamel etching in two levels (with and without). Materials were stained with 0.02 mg/mL ethanolic solution of tetramethylrhodamine isothiocyanate. Bovine enamel samples (4 × 4 mm) were immersed in 0.01 M HCl, pH 2.3, for 30 seconds to produce initial eroded lesions. Afterward, the materials were applied on half of sample enamel surface following the manufacturer's instructions. On the other half of sample, the materials were applied without etching the enamel. Materials penetration into the enamel was assessed by Confocal Laser Scanning Microscopy on reflection and fluorescence modes. The penetration depth (PD) was measured using ImageJ software. Data were analyzed by two‐way ANOVA and Tukey test (P < 0.05). Regardless of the material, etched enamel resulted in higher PD than non‐etched (P < 0.05). Icon^® showed the highest PD in enamel followed by Helioseal Clear^® (P < 0.05), with significant difference between them (P < 0.05) and no difference was found among AdheSE^®, Tetric N‐Bond^®, and Single Bond 2^® (P > 0.05). It can be concluded that prior enamel etching increased the materials penetration into eroded enamel and the Icon^®—infiltrant presented highest penetration. Microsc. Res. Tech. 79:72–80, 2016. © 2015 Wiley Periodicals, Inc.     

渗铜剂成分对烧结钢渗铜性能的影响

采用纯Cu粉、Cu-2Zn粉、Cu-2Fe粉、Cu-2Zn-2Fe粉等4种不同成分的渗铜剂,以Fe-Cu-C烧结钢为基体,在1 120～1 150℃、保温30 min工艺下渗铜,研究不同成分渗铜剂的熔渗性能及其对渗铜烧结钢力学性能的影响。结果表明:同其它3种渗铜剂相比,Cu-2Zn-2Fe渗铜剂渗铜性能最好,烧结钢渗铜后表面质量均匀一致、无溶蚀现象;上下表面硬度基本一致,较未渗铜烧结钢提高了约60%;4种渗铜剂渗铜的烧结钢冲击韧性为13.7～14.0 J/cm2,较未渗铜的提高2倍以上;在渗铜剂中,Fe元素可以降低渗铜剂熔体活性、增加黏度;Zn元素可以降低渗铜剂熔体黏度、增加其活性。     

砂轮浸渗剂的作用机理及其合理选择

本文介绍了砂轮浸渗剂在干磨环境下的作用机理，即冷却、润滑、防堵塞和降低空气污染等作用，分析了磨削过程中浸渗剂与加工表面的反应及其效用。提出了硫、磷、氯系极压反应膜在生成条件、生成速度以及耐负荷性上的差异。提出了根据具体的加工条件和砂轮特性优化选择与之相适应的浸渗剂类型。     

INFILTRATION MECHANISM AND QUALITY CONTROL OF CONTACT MATERIALS

The infiltration mechanism, which has great significance for the quality control of electrieal contact material made from W-Cu, W-Ag alloys with high content of tungsten, has been studied. And a directive infiltration technology for improving the product quality and gaining a better economic benefit has been developed.