| Erosion wear is one of the common problems in the application of engineering materials leads to huge energy losses and wastes. Therefore, study on technical problems of wear resistance protection materials is very significant. Currently liquid phase sintering and solid state sintering are often applied to prepare common used abrasion resistant ceramics. Because of the larger volume change after sintering, it is very difficult to fabricate large-size products with complex shapes. To solve this problem, Si3N4-SiC composite was fabricated by reaction sintering in this study. The influences of Si and SiC addition on mechanical properties of the composite were investigated. Also, the solid-liquid phase erosion-wear behaviors were studied and the erosion wear mechanisms were analyzed based on the observation of the micro-morphology of samples after abrasion.Si and SiC were used as raw materials, Si3N4-SiC composite was fabricated by semi-dry cold isostatic pressing and reaction sintering. The results shows that the sintering linear change rate of samples were less than 0.8%, maintained their outline dimensions well. Bulk density, flexural strength and compressive strength increased with the increase of Si addition, flexural strength and compressive strength reached the largest values of 233.1MPa and 235.90MPa respectively when Si addition was 100wt%. Hardness of the samples increased at first and then decreased with the increase of SiC particles. When the content of SiC was 30wt%, the maximum HRC hardness of 58.50 is achieved.Under the conditions of erosion medium water and SiC mixed particles, average linear velocity 132.13m/min, erosion wear resistance of samples with 40~80wt% Si content was better than that of 95 Al2O3 abrasion resistant ceramic. Solid-liquid erosion wear resistance reaches the best when Si content was 70wt%, the erosion rate was only 0.87%. Under the conditions of the same erosion medium, average linear velocity 66.82m/min, erosion rates of all samples (including 95 Al2O3 abrasion resistant ceramic) had little difference with the maximum is 0.40% and the minimum is 0.30%.The micro-morphology of samples after abrasion was observed and the erosion wear mechanisms were also analyzed. It indicates that the"shielding effect"of SiC particles when the erosion medium acting on the surfaces of samples alleviated the speed of erosion and destruction, and this effect degree increased with the increase of SiC particles to some extent. When SiC content is 30wt%, it reached the best. When SiC content continued to increase, the matrix-phase Si3N4 content decreased, leading to the weakness of the bonding between phases and the increase of erosion rates of samples. |
