Study on the geopolymers has been a history of nearly 40 years, because of its huge comparative advantage and attractive prospect, has become a hot research field of international materials.In this paper, based on the history and the present status of geopolymers cementitious materials development, summarized geopolymer cementitious material in the selection of raw materials, the activation agent development,preparation process research, cementitious material properties, mechanical properties, durability and engineering applications. progress made and trends.On this basis, expounded the problem of large-scale widely used the geopolymers need to continue to address, and pointed out the direction for its further research and application.
Seawater and sea sand mixed in concrete will cause rebar of structural concrete corrosion, referring to the principles of composition and design of MCI and Pearson’s Hard-Soft Acid-Base (HSAB) theory, as well as to synergy effect of corrosion inhibitor applied in chemical industry, compound corrosion inhibitor has been designed consisting of diisopropanolamine, surface active agent, inorganic salts and so on. This paper research the relation between polarization potential and time of rebar in seawater-and-sea sand concrete through a series of experiments by adding corrosion inhibitor into seawater-and-sea sand concrete to improve its corrosive resistance characteristics. The results indicate that Z5 has the best inhibition effect. Corrosion inhibitor Z5 comprises 50% of triethanolamine, 20% of dimethylethanolamine (DMEA), 25% of triethoxysilane and 5%lithium nitrate, and its proper content applied in seawater-and-sea sand concrete is 1.5%. Rebar have been embedded in seawater-and-sea sand concrete for the long-term test. The results show that corrosion resistance performance of seawater-and-sea sand concrete with corrosion inhibitor Z5 was significantly improved, and the embedded bar was not corroded at all within 420 days.
As a new type of building material, Basalt Fiber Reinforced Plastics is employed in concrete in place of steel reinforcement under such strongly-corrosive environment as marine engineering projects to avoid durability problem caused by corrosion. But BFRP bars’ alkali-resistance must be considered and studied. In this study, BFRP was soaked in saturated Ca(OH)2 solution and its tensile strength was measured through long-period immersion and high-temperature immersion experiments respectively. Besides, accelerated high-temperature method was adopted to detect its main ingredients: continuous Basalt fiber and resin. The results indicate that BFRP has poor alkali-resistance and its alkali-resistance must be improved if it is applied in concrete for long-term purpose.
In order to enhance the lubricating capacity of the magnetic lubrication on the surface of the porous material, a new magnetic lubricating field has been designed by simulating method based on the coupling relationship between the pores and micro-magnets structure. The results show that the output characteristics of magnetic fluids in the pores of the material play a significant role in the design, whereas the output characteristics depend on micro-magnets and the pores’ size such as length and diameter, for example, when the ratio of length/diameter of the pore is larger than 3.2 ,the output capacity of the magnetic fluids in the pores presents a stable value, but when the ratio is smaller than 3.2, the output capacity obviously decreases. It is also found when the distance among the pores changes from 5 mm to 8 mm, the output capacity also presents a stable value; however, the output capacity obviously decreases with the increased distance among the pores beyond 8 mm. Furthermore, the effect of the parameters of micro-magnets structure on the output capacity of magnetic fluids is also investigated in the paper. The research results are helpful to improve the lubricating properties of the magnetic fluids on the surface of the porous material.
The effects of Young’s modulus of materials on the rolling resistance characteristics of ball bearing have been investigated by experimental,analytical and numerical method. Results show that the Young’s modulus of ball bearing greatly affects its rolling resistance characteristics and the characteristic values of the rolling resistance characteristics will decrease with the increase of the Young’s modulus of ball bearing, for example, the elastic power consumption of the ZrO2 bearing is about 80 percent of the GCr15 bearing, and that the effects mainly reflects on three aspects: the elastic hysteresis of the material, the contact stress and deformation in the contact region.Results are helpful to the design of materials compatibility of ball bearing.
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