Hao Ran Sun

Study on Properties and Application of PG/CS Composite PCMs

Tris (hydroxymethyl) ethane (PG) as a phase change material, micro-porous xonotlite (CS) as matrix, PG/CS composite PCMs were prepared by melt-soaking method, and the effect of micro-porous structure of xonotlite on heat absorption capacity, bending strength and insulation performance of composites, and the exudation of PG was studied. Otherwise, for the work environment and characteristics of propulsive device of vehicle, this paper explored the feasibility that phase change materials (PCMs) worked as the insulation material in short-time insulation system of the vehicle. Experimental results show that, when the most probable pore diameters of xonotlite was not less than 63nm, the composites presented better and almost same absorption capacities of matrix (CS) to PCM (PG) in different composites; when up to 85nm, the composite exhibited the lowest leakage rate (less than 5%), the optimal mechanical property and thermal insulation performance. This Study proposed a new idea for the design of the insulation material in the thermal protection system of propulsive device of vehicle.

Preparation and Properties of Polyalcohol Phase Change Material for Insulation

In this paper, the composite phase change materials for insulation were prepared by melt-soaking method. Trimethylolethane (PG) was chosen to be the phase change material (PCM) and two kinds of porous materials as the supporting matrices separately. The effects of both matrices to PG were analyzed by X-ray diffraction (XRD), and the heat insulation properties of composites were evaluated by Plat heat insulation test device. At last, microstructures of composites were observed by scanning electron microscope (SEM) and their effects to composites were discussed.

Effect of Additives on Bond Property for Phenolic Resin-Based Adhesive

Modified phenolic resin-based adhesive is used as the high temperature binder, which is prepared by adding different additives, zirconium diboride, boron carbide as modified fillers, and H3PO4, AlPO4 as curing agents. The influence of additives for phenolic resin-based adhesive on bond property of SiC ceramic was studied after heat treatment at 400 oC , 800 oC , 1200 oC , 1600 oC. The results show that the improvement of adhesion property for curing agents is not obvious. B4C modified phenolic resin-based adhesive exhibits better adhesion performance than ZrB2 modified phenolic resin-based adhesive. Bonding property of B4C modified phenolic resin-based adhesive is best at 1200 oC , and the adhesive strength is reduced above 1200 oC along with rising of the heat treatment temperature. Because of the formation of shrinkage micro-defects of phenolic resin, bond strength exists a sharp decline after 1200 oC heat treatment.

Optimized Design of Multilayer Thermal Insulations for Hypersonic Vehicles

In this paper, high temperature multilayer thermal insulations were to investigate in thermal protection systems for hypersonic vehicles. The thermal response and thermal property of the multilayer insulations were simulated and analyzed by using Ansys software. The calculation results were analyzed and the effects of parameters such as layer thermal conductivity, layer thickness, layer density, and numbers of layer are clarified. Thermal property of multilayer insulations was optimized. The results are helpful to the optimum design of the multilayer insulation system.

Preparation and Microstructure of (La0.5Sm0.5)2(Zr0.7Ce0.3)2O7 Ceramics Prepared by Chemical Coprecipitation Method

Ceramic materials of (La0.5Sm0.5)2(Zr0.7Ce0.3)2O7 composition powder was synthesized by chemical coprecipitation method using Sm2O3, La2O3, Ce (NO3)3·6H2O and ZrOCl2·8H2O powders as raw materials. Microstructure and phases of (La0.5Sm0.5)2(Zr0.7Ce0.3)2O7 (LSZCO) powder was examined by Transmission Electron Microscope (TEM) and X-ray diffraction (XRD). The specific surface area of powders were determined by BET specific surface area test. The structure of LSZCO powder remained in pyrochlore with the increase of temperature more than 1200 °C. According to the impact on the specific surface area of LSZCO powder, the factors of the process is ordered in descending sequence as follows: pH value, dispersant content, concentration of reactants, the reaction temperature.

High Temperature Micro Structural Evolution of ZrO2 Fibers Thermal Insulation Materials

Yttria-stabilized zirconia fibers thermal insulation materials may be the main developmental direction of high temperature thermal protection materials, due to their high temperature resistance (above 2000 °C), high strength and toughness, low thermal conductivity ( about 2 W/m·K), oxidation resistance and other excellent properties. However, mechanical property of zirconia fibers thermal insulation materials is decrease after high temperature heat treatment. In this paper, the evolution of microscopic structure of zirconia fibers is studied by using the method of oxyacethlene ablation. The gain growth and high temperature creep are observed after 600 s heat treatment at 1800 °C. Crystal phase of zirconia fibers is not changed and still cubic. Moreover, crystallinity is more higher form XRD patterns. Controlling grain growth can improve high temperature mechanical property of zirconia fibers thermal insulation materials.

Preparation and Performance of Zirconia Fiber Board

Zirconia fiber not only can be used for a long time in 1600°C, but also has low thermal conductivity at high temperature. Due to the excellent insulation performance, it has a broad application prospect in aerospace, aviation, energy and other areas. In the present study, we chose yttrium stabilized zirconia fibers and nanometer zirconia powder as main material and adding soluble starch, zirconium sol as low temperature and high temperature binder. Rigid zirconia fiber board was prepared by material slurry, filter shaping, stripping drying and high temperature calcination. After high temperature calcination of 1600°C for 12h, sample pore are mainly concentrated in 25-75μm, bending strength performance is best when the adding amount of nanometer zirconia powder was 7%, the thermal conductivity is only 0.132 W·m-1·K-1 at 1400°C.

Effect of B4C and SiO2 on Bond Property for Phenolic Resin-Based Adhesive

In this paper, the modified phenolic resin-based adhesive was prepared by dissolving different components. After low temperature curing, SiC samples were bonded by the binder. The samples were treated at different temperatures (400°C, 800°C, 1200°C, 1500°C) under an inert atmosphere. The bonding strength of samples was tested after heat treatment at room temperature. The results showed that the bonding strength of the B4C modified phenolic resin (PF) based adhesive is the highest. When the heat treatment temperature was above 1200°C, the bond strength increased with the additive amount of boron carbide at room temperature. The microstructures of the samples were observed by optical microscope and scanning electron microscope. The effects of the modified filler and heat treatment temperature on the bonding strength of the phenolic resin based adhesive were investigated. The bonding strength of boron carbide-modified phenolic resin-based binder was tested under high temperature. It was found that the bond strength at high temperature was lower than that at room temperature, and the bond strength decreased with the increase of temperature.

The Study of Heating Mode of an Expansion Insulation Material

A new kind of alumina fiber-based expandable insulation material was designed using expandable graphite, alumina fiber and aluminum phosphate adhesives, and fabricated through wet mixing, vacuum suction filter, pressure drying. This material had 100%-300% of volume expansion ratio under temperatures from 400 to 1000°C, well heat insulation performance and mechanical property after expansion. Due to the special expanding property of expandable graphite, the heating mode will seriously impact on the properties of material. In this paper, the influence of two different heating-up modes on the material properties had been studied. At slowly heating-up mode, the expansion ratio almost maintained at 115%, and the compression strength increased visibly comparing with fast heating-up. At one-side heating-up mode, the expansion ratio was lower than the all-side heating-up mode, which respectively were 164.9 % and 226.9% at 800°C, and the compression strength increased slightly because of the extension of heat treatment time.

Preparation of Camphene Carbon/Silicon Carbide Slurry for 3D Printing

The 3D printing ceramic body was prepared by camphene carbon/silicon carbide slurry, which were prepared with camphene, carbon and silicon carbide, dispersant, binder as rawmaterial, according to certain stoichiometric ratio. The effects of the choice of dispersants on the dispersion of the slurry performance were investigated. The amount of dispersant were determined.