原位自生NbC/H13钢复合材料抗磨损性能研究

H13钢作为盾构机刀圈材料,主要用于破碎坚硬岩石。在盾构机掘进过程中,刀圈的磨损是不可避免的,过度的磨损会导致掘进效率的降低,增加施工风险。为了提高H13钢的耐磨性,采用重力铸造原位自生的方法,制备了体积分数为1%、3%、5%的原位自生NbC/H13钢复合材料。采用金相显微镜、扫描电子显微镜对复合材料的物相组成与组织结构进行分析,使用冲击试验机、三体磨料磨损试验机对不同体积分数NbC/H13钢复合材料的冲击韧性、磨料磨损性能进行研究。结果表明,制备的复合材料组织致密,NbC增强相在基体中弥散分布。随着增强相体积分数提高,增强相的形态由网状逐渐向小棒状和颗粒状转变;复合材料的冲击韧性值随着增强相的体积分数提高逐渐下降,当NbC含量在5%(体积分数)时,冲击韧性到最小值6.5 J;三体磨料磨损结果表明,随着NbC体积分数的增加,有效减少磨料对钢基体的磨损,从而进一步提高了复合材料的耐磨性,与基体材料相比,耐磨性提高了2.1倍。

ZrO_(2)增韧Al_(2)O_(3)陶瓷颗粒对增强高铬铸铁基复合材料冲击磨料性能影响

传统的耐磨钢铁材料难以满足现代矿山装备对关键耐磨部件的需求,陶瓷颗粒增强钢铁基耐磨复合材料成为最具良好应用前景的耐磨材料之一。通过预烧结获得不同体积分数及不同颗粒大小的陶瓷预制体,结合铸渗法制备出氧化锆(ZrO_(2))增韧氧化铝(Al_(2)O_(3))陶瓷颗粒增强高铬铸铁(HCCI)基复合材料。结果表明:随着ZTA(ZrO_(2)增韧Al_(2)O_(3))颗粒体积分数(25%~45%)的增加,ZTA颗粒等效直径(1.7,1.2,0.4 mm)减小,复合材料抗冲击磨损性能随之提高,以颗粒体积分数为45%、等效粒径为0.4 mm时最佳。ZTA p/HCCI复合材料的主要磨损特征是磨损面发生微切削,其主要磨损机制是磨料磨损。

Optimization of Quenching Process for ZTAP/ High Chromium Cast Iron Composites

In order to solve the problem of cracking of ZTAP(Zirconia toughened alumina ceramic particles)reinforced HCCI(high chromium cast iron)matrix composites,the quenching process was optimized.ZTAP reinforced HCCI matrix composites were prepared by infiltration method with gravity sand casting.The thermal expansion curves of HCCI and the composites were measured at different cooling rates by Glebble-3500.The microstructure of the HCCI matrix and the composites were characterized by X-ray diffraction,light microscopy,SEM,ESD,and EPMA.The tested mechanical properties include Rockwell hardness and impact toughness.The deformation differences of HCCI and the composite at different cooling rates were obtained according to the test results of thermal expansion coefficient curve and changes in microstructure and mechanical properties,and air cooling was the most favorable for the composites to have good hardness and not easy to crack.The cooling rate during air cooling is approximately equal to 21℃/s in this work.When the quenching process was air cooling,the impact toughness and hardness of the composites are 3.7 J/cm^(2) and 61.8 HRC,respectively,and the deformation difference between the composites and HCCI was 20μm at 300℃.

离心铸造复合辊材料及技术研究进展

近年来,低成本、长寿命、高生产效率是复合辊技术的主要发展方向。列举了一些典型的离心铸造复合辊的工业部件,如双金属复合轧辊、磨辊辊环,并对国内外不同工艺、不同材料的辊环性能进行对比,发现离心铸造复合辊性能优良、寿命高,在水泥、矿山行业中得到广泛使用。综述了复合辊的材料选择以及技术发展,指出采用球墨铸铁、高铬铸铁、高锰钢、高速钢等多种材料复合的方式可以提高不同工况下工件的使用寿命,降低成本。总结了冷却速率、浇注温度、离心转速、浇注时间等工艺参数对离心铸造颗粒增强金属基陶瓷复合辊组织和性能的影响。最后,提出了目前离心铸造复合辊存在的主要问题及可能的发展方向。