Process of graphitization in gray cast iron under pressure

Conclusions  

Eutectic solidification mode of spheroidal graphite cast iron and graphitization

The shrinkage and chilling tendency of spheroidal graphite (abbreviated SG) cast iron is much greater than that of the flake graphite cast iron in spite of its higher amount of C and Si contents. Why? The main reason should be the difference in their graphitization during the eutectic solidification. In this paper, we discuss the difference in the solidification mechanism of both cast irons for solving these problems using unidirectional solidification and the cooling curves of the spheroidal graphite cast iron. The eutectic solidification rate of the SG cast iron is controlled by the diffusion of carbon through the austenite shell, and the final thickness is 1.4 times the radius of the SG, therefore, the reduction of the SG size, namely, the increase in the number, is the main solution of these problems.     

Novelties in the theory of graphitization. Modification of cast iron by inoculation

Conclusion The theory of modification of cast iron by inoculation has been enriched by new development. In the light of this theory attention must be given mainly not only to the nucleation of centers of graphitization in modification but also to the increase of their life when the melt surrounding them is still sufficiently superheated.The introduction of the recommendations of the modern theory into industrial practice should yield savings of many millions in Soviet cast iron production. Moreover, the organization of production of foundry ferrosilicon does not require any additional capital investments.Tashkent Polytechnic Institute. Vinnitsa Polytechnic Institute. Production Association "Kurgansel'mash." Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 2, pp. 11–18, February, 1989.     

球墨铸铁加热过程中渗碳体石墨化的原位观察

采用激光共聚焦扫描显微镜直接观察了球墨铸铁在加热过程中渗碳体的分解和石墨形态的演化。结果表明：球墨铸铁在加热过程中渗碳体逐渐溶解,加热速率越快,渗碳体的分解速率越快。加热过程中石墨形态的演变行为与加热速率有关。加热速率较慢,组织中出现了小石墨,原有石墨长大。加热速率较快,渗碳体周围的小石墨逐渐溶解变小。     

Development of boron white cast iron

Abstract

With boron substituting for carbon in cast iron composition and eutectic borides substituting for eutectic carbides in microstructure as the hard wear resistant phase, a new kind of wear resistant white cast iron has been developed. The microstructure and mechanical properties of this new white cast iron both in the as cast state and after appropriate heat treatments were studied. The results show that the as cast microstructure of the boron white cast iron comprises a dendritic matrix and interdendritic eutectics, and the eutectic compound is that of M₂B or M′_0˙9Cr_1˙1B_0˙9 type, where M represents Fe, Cr or Mn and M′ represents Fe or Mn. The morphology of the eutectic borides is much like that of carbide in high chromium white cast iron, but the hardness of boride is higher than that of carbide. The matrix in as cast microstructure comprises martensite and pearlite. After austenitising and quenching, the matrix mostly changes to lath type martensite and the eutectic borides remain unchanged. In addition, two different sizes of particles, with different forming processes during heat treatment, appear in the matrix. The boron white cast iron possesses higher hardness and toughness than conventional white cast iron and nickel hard white cast iron, and has a better balance between hardness and toughness than high chromium white cast iron.     

氢等离子体在铁催石墨化作用下对CVD金刚石膜的刻蚀

在铁薄膜的催石墨化作用下研究了用氢等离子体刻蚀由微波等离子体化学气相沉积（MPCYD）制备的多晶金刚石厚膜的表面。其工艺为：自支撑的金刚石厚膜浸入饱和的三氯化铁水溶液中，然后平放在大气环境中干燥，将处理过后的金刚石膜放入MPCVD装置中，先用氢等离子体将氯化铁还原成铁，然后在800℃左右的温度下，利用铁对金刚石的催石墨化作用及氢等离子体的刻蚀作用将其表面刻蚀。刻蚀完后的金刚石用酸清洗，在丙酮溶液中漂洗，然后用SEM观察刻蚀效果，用Raman光谱对表面碳的结构进行了表征。最后用机械研磨法对金刚石样品表面进行研磨，并对研磨结果进行对比。实验结果表明，这种方法能够有选择地快速刻蚀金刚石膜的表面，破坏表面晶粒的完整度，降低表面耐磨性，从而提高对粗糙金刚石膜表面研磨的效率。     

Phase composition of high-chromium white cast iron

Conclusion The change in hardness after annealing of cast iron and after normalization at temperatures up to 1100° is due to the structural condition of phase, while the reduction of the hardness when the normalization temperature is raised from 1100 to 1200° is due to the appearance of austenite. The presence of a substantial amount of austenite also explains the low hardness of the cast iron in the cast condition as compared with the hardness after normalization at 1000–1100°. The high hardness of the cast iron normalized at 1000–1100° may be due partially to the precipitation of secondary carbides.Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 12, pp. 59–61, December, 1977.