Carbon fibers (CFs) has been a hotspot in composites as a reinforcing phase. The types and dispersion methods of CFs and the methods for evaluating their dispersibility in cement⁃based composites, the preparation process of CFs surface coating modification and its advantages and disadvantages were reviewed. The coating modification treatment could prepare carbon fiber reinforced cement⁃based composite materials (CFRC) with good performance. At the same time, the influential factors of CFRC mechanical properties were systematically discussed and studied, including water⁃cement ratio, including water⁃cement ratio, curing age, molding process, silicon powder content, additives, CFs content and length, etc.It is concluded that the key to further improving the mechanical properties of CFRC is to improve the dispersion and compatibility of CFs in the cement matrix, and provide a reference for the future preparation of high⁃performance CFRC.

The composite PCM was prepared by vacuum impregnation method. Natural bentonite and lauric acid (LA) were used as supporting material and PCM, respectively. The results show that the addition of flake graphite not only improves the thermal conductivity of the composite phase change material, but also prevents the phase change material from leaking out of the composite phase change. After 200 thermal⁃cold cycling treatment, the prepared form⁃stable composite PCM still shows a good performance of thermal reliability and has potential to be used in the thermal energy storage system.

Different batches of multidiameter shafts used for rail truck, produced by 0Cr16Ni5Mo in a factory, were tested, analyzed and researched by many testing techniques. They were chemical composition analysis, mechanics performance testing, ultrasonic flaw detection, microstructure observation, areascan of elements and energy dispersive spectrometer analysis. The results showed that the products smelted in a dualprocess and forged in different stage could meet technical requirement. The smelting process was smelting in vacuum induction furnace and electroslag remelting. Diameter of the electrode bar was 330 mm and diameter of the steel ingot smelted was 610 mm. Some conclusions were drawn in this paper. One was that the accurate control on chemical component of the electrode bar could be achieved by setting correct parameters on the frequentness of whisking and temperature in refining period. The other was that the gaseous oxygen content also reduced from 66×10^-6 to 30×10^-6. Besides, detailed optimized parameters of Multidiameter shaft produced by 0Cr16Ni5Mo in the process were determined. The smelting frequency was 150 Hz. The whisking rate of flow with gaseous Ar was 70～80 L/min and the whisking frequency 65 Hz. The temperature of the homogenized diffusion process was 1 150 ℃ for 3 h and 1 050 ℃ for 5 h. The tonnage in the stage of upsetting and molding were 3 500 and 2 000 respectively.

According to the domestic and foreign scholars on the research status of GFRP concrete column, the hollow reinforced concrete column confined by GFRP tube was put forward as a new type of member. Three hollow GFRP reinforced concrete columns were designed, and the compression capacity under three kinds of reinforcement ratio through the static test method was investigated. At the same time, the simulation analysis was carried out on the specimens combining with the finite element software ANSYS, a reference for practical engineering was provided. The results show the bearing capacity of specimen increased with the increase of reinforcement ratio, but not linear relationship. With the increase of reinforcement ratio, the confinement effect of composite columns increased firstly and then decreased. When the longitudinal reinforcement ratio of the new type of composite columns was 0.9%, the loading mechanism was best, and the confinement effect by the GFRP tube was largest.