42CrMo轧辊激光熔覆TiC-VC增强铁基熔覆层性能

Properties of in-situ formed TiC-VC particle reinforced Fe-based alloy composite coatings produced by laser cladding on 42CrMo roller

采用同步送粉方式,在42CrMo轧辊基材上利用钛铁、钒铁和石墨等通过激光熔覆原位自生反应,制备了成型良好、致密无气孔、无裂纹、与基体呈冶金结合的TiVC2增强铁基熔覆层.利用X射线衍射、电子探针、显微硬度计、电化学工作站研究了熔覆层的显微组织及性能.结果表明,熔覆层中碳化物为TiVC2,TiVC2大小约0.5～2.0μm,呈多角块状均匀分布,碳化物对应两种不同的形核机制：以氧化铝异质形核和碳化物自发形核.随着熔覆合金粉末中TiC-VC数量的增加,熔覆层硬度并不呈简单的线性增加,熔覆层的耐蚀性逐渐变差.

With femtosecond laser pulse shaping technique,the coherent control of non-resonant two-photon transition in a molecular system （perylene dissolved in chloroform solution） is studied theoretically and experimentally.The femtosecond pulse is shaped with simple phase patterns （cosinusoidal and π phase step-function shapes） and it is found that the two-photon transition probability in molecular systems can be reduced but cannot be eliminated.Coherent control of non-resonant two-photon transition in a molecular system is correlated with both the laser field and the molecular absorption bandwidth.In contrast with atomic system,control efficiency of two-photon transition in molecular systems is reduced.