The paper studied preparing sand-lime bricks by pressure shaping and nature curing, discussed the stimulation effect of compound activators composed of phosphogypsum and lime. The result shows that: when the proportions of raw materials are as follows: 10~15% weight content is iron ore tailings, 3% is phosphogypsum, 5% lime, 5% cement, 40~45% low quality fly ash, and 22~37% chips, the strength of sand-lime bricks produced gets its highest. XRD and SEM are used to characterize its mineral composition and microstructure. The paper also discussed the relationship between structure and performance inside the bricks, and its hydration mechanism.
A kind of low-heat Portland cement clinker was prepared with coal gangue, limestone and gypsum through optimizing the mix proportion of raw materials, and its properties and hydration characteristics were studied. The results showed that the cement clinker meeting the demands of mid (low)-heat Portland cement standard could be prepared with 35% (by weight, the same below) coal gangue, 57-60% limestone and 6-8% gypsum. The raw materials were burned at 1380°C for 40 minutes. The main hydrates were calcium silicate hydrate (C-S-H) gel, ettringite (AFt), monosulfate (AFm) and Ca(OH)2.
This work concentrated on being able to predict the resistance properties of Y-shaped branch pipe in gas-solid two phase flow. Y-shaped branch pipeline with one branch angle keeping constant and the other being changeable experimental system was built up. Micro-glass bead and millet with similar particle diameter and different solid density were conveyed in the experimental system. As a result, trends of pressure drop on each branch pipe were expressed to perform resistance properties. It can be concluded that pressure drop of the two materials had similar trend and was significantly affected by the branch angle and gas velocity. Meanwhile, the deposition velocity was defined in this study. The relationship between the solids loading ratio and pressure drop on each branch pipe was given based on experimental data, which agreed the theoretical analysis well.
SiC coatings were fabricated by the Rapid Chemical Liquid Deposition (RCLD) on the surface of graphite, the influence of deposition temperature on the microstructure of SiC coatings was investigated, the oxidation behaviors of SiC coatings at different temperatures were analyzed. The results indicated that the optimum condition for the SiC coatings are at 1150°C, a smooth and dense coating will be obtained, the thickness of the coatings are between 80~120μm. The oxidation resistance test results indicated that after oxidation at 1000°C for 5h, the mass loss of the sample is only 21%.
Adopting two-step deposition processes, SiC concentration gradient layer on the surface of Cf/C composites were prepared via Self-heating Chemical Liquid Deposition (SHRCLD) technique. In second deposition process, carbon and SiC were codepositted from pure kerosene and TEOS. The temperature of deposition was 1000°C~1200°C and the system pressure was 0.1MPa. Different thickness of gradient layers would be attained via adjusting the proportion of TEOS in procurer and controlling deposition time. Oxidation resistance, and mechanical tests were investigated, and the microstructure was observed under SEM. Results showed that the flexural strength of the composites was 123.7 MPa. The antioxidation temperature of Cf/C composites with the gradient layer is up to 800°C in air. The process of SHCLD technique is simple and easy to be controlled, and the deposition rate is faster than other conventional technique.
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