In order to achieve self-repairing of MgO-C refractory in oxidizing atmosphere at high temperatures, Fe powder, serving as both antioxidant and direct-bond former, was introduced into this refractory. The effect of Fe addition on the microstructure, properties and oxidation resistance was investigated. The coexistence of (Mg,Fe)Oss and Mg(Fe1.2Al0.8)O4 was identified for the Fe-containing MgO-C refractory after graphite was oxidized, by which a network was formed in the matrix. As a consequence, both densification and direct-bond in the oxidized layer were greatly enhanced compared with the conventional MgO-C refractory, solving the issue of strength degradation during high temperature oxidation. An excellent oxidation resistance was obtained owing to the above improvements.

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In the pipeline system for slurry, local erosion wear failure has become the main damage mechanism of pipe in the fracturing operations of oil-gas engineering. Computational Fluid Dynamics simulation is performed to determine the evolutionary process of erosion wear in tubing connector, which is the resistance of pipeline system, and a new way to predict the pipeline longevity is provided. Based on the Euler equation, solid particle concentration in the slurry and interphase momentum exchange are included in the liquid flow equations due to the influence of dense particle on slurry (slurry is a two-phase flow), and the particle trajectory were calculated in the Lagrange frame by analyzing the forces from the interaction of liquid and particle and particles impact. With the erosion damage model, the erosion rate/depth in the connector was calculated to reconstruct the mesh model of shoulder with 5 tori. Torus 1 is closest to axis while torus 5 is on the outmost wall of the connector. During the erosion event, greatest erosion and hence surface deformation occurs on tori 1 and 2, and this affects the surrounding flow and particle movement. After 10 hours of erosion, there was a dramatic drop in the maximum erosion rate, which illustrated a conservative prediction for pipeline service life if the initial erosion rate was used. An erosion experimental setup was also performed to identify the weight loss and erosion characteristic of the inner surface with erosion time of 55 hours. It was observed that the erosion simulations provided relative errors within 18% for erosion length and weight loss compared to the experimental values and a closed form equation for the erosion rate was proposed to predict the erosion life of tubing connector

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