In this study, a TiC-reinforced composite coating was produced to improve the wear resistance of a pearlite matrix grey iron using a pre-placed Ti powder by laser cladding. Results of scanning electron microscopy (SEM), X-ray diffractometer (XRD), and energy dispersive X-ray spectroscopy (EDS) confirmed that the coating was composed of TiC particles and two kinds of α-Fe phase. The fine TiC particles were only a few microns in size and uniformly distributed on the matrix phase in the composite coating. The microstructure characteristic of the composite coating resulted in the microhardness rising to about 1000 HV0.3 (China GB/T 4342-1991) and the wear resistance significantly increased relative to the substrate. In addition, the fine and homogeneous solidification microstructure without graphite phase in the transition zone led to a good metallurgical bonding and transition between the coating and the substrate. It was of great significance for the cast iron to modify the surface and repair surface defects or surface damage.

In this paper, a TiC reinforcement metal matrix composite coating is produced using nickel and graphite mixing powder on the surface ofTi-6Al-4V alloy by laser radiation. The microstructure of the coatings is investigated by XRD, SEM and EDS. Results show that most of the TiC phase is granular, with a size of several micrometers, and a few of the TiC phases are petals or flakes. At the cross-section of the coatings, a few special TiC patterns are found and these TiC patterns do not always occur at the observed cross-section. The even distribution of the TiC phase in the coatings confirms that the convection of the laser-melted pool leads to the homogenization of titanium atoms from the molten substrate, and carbon atoms from the preplace powder layer, by the mass transfer. The characteristics of the TiC pattern confirm that the morphology and distribution of the primary TiC phase could be influenced by convection. Two main reasons for this are that the density of the TiC phase is lower than the liquid melt, and that the primary TiC phase precipitates from the pool with a high convection speed at high temperature.

The low cost and high abundancy of nickel makes it highly attractive for both industrial and academic researchers in the field of polyolefin. However, the development of high performance nickel catalysts for ethylene homo and copolymerization is highly challenging. In this contribution, two novel cationic nickel catalysts with quinone backbone and sterically hindered aryl substituents on phosphine have been synthesized and supported on solid supports to prepare heterogeneous catalysts. The homogeneous catalysts showed high activity and high thermal stability in ethylene polymerization. After heterogenization of these catalysts, all the polymerization parameters (polymerization activity, thermal stability, and polymer molecular weight) were significantly improved. The heterogeneous catalyst can achieve activity of up to 3.26 × 106 g mol−1 h−1, along with polyethylene molecular weight of up to 81.8 × 104 g mol−1. More importantly, these homogeneous and heterogeneous catalysts can realize copolymerization of ethylene with a series of polar comonomers such as methyl 10‐undecenoate, 10‐undecenol, and 6‐chloro‐1‐hexene.

Author Contributions: Yanhui Liu and Zhishui Yu conceived and designed the experiments; Yanhui Liu, Jieqiong Ding and Weicheng Qu performed the experiments; Yanhui Liu, Jieqiong Ding and Zhishui Yu analyzed the data and discussed the experiment; Yanhui Liu wrote the paper. The manuscript was reviewed by all authors.