柴石滩水库混凝土面板堆石坝垫层料制备工艺

利用爆破开采筛分加砂掺拌法生产、制备混凝土面板堆石坝垫层料，在质量上满足设计要求，在生产上容易实现高强度大方量生产且经济效益明显。

STEADY HEAT TRANSFER ANALYSIS AND PARAMETER OPTIMIZATION FOR MULTILAYER THERMAL INSULATIONS

The energy equilibrium equation and discrete ordinate methods are combined to establish the one-dimensional steady heat transfer mathematical model of multi-layer thermal insulations （MTIs） in metallic thermal protection systems. The inverse problem of heat transfer is solved by the genetic algorithm and data from the steady heat transfer experiment of fibrous thermal insulations. The density radiation attenuation coefficient, the albedo of fibrous thermal insulations and the surface emissivity of reflective screens are optimized. Finally, the one-dimensional steady heat transfer model of MTIs with optimized thermal physical parameters is verified by experimental data of the effective MTI conductivity.

Experimental investigation on heat transfer characteristics of a new radiant floor system with phase change material

In order to improve the heat transfer characteristics of the traditional phase change material（PCM） floor, a new double-layer radiant floor system with PCM is proposed, which can store thermal or cold energy in the off-peak period and use them in the peak period. An experimental setup was developed to study the heat transfer characteristics of the new system under both cooling and heating modes. The experimental results show that the double-layer radiant floor system with PCM can meet both the cold and thermal requirements of users. Moreover, with the same duration of the thermal energy storage process, the increase of water temperature supplied to the system can improve the heat transfer characteristics of the system but lead to the discomfort of users. On the other hand, if the air temperature at the end of the thermal energy storage process is the same under different conditions, the increase of supplied water temperature will decrease the thermal energy storage time and ensure the comfort of users.

Influence of carbon coating prepared by microwave pyrolysis on properties of LiNi_(1/3) Mn_(1/3) Co_(1/3) O_2

A novel synthesis method of carbon-coated LiNil/3Mnl/3COl/302 cathode material for lithium-ion battery was reported. The carbon coating was produced from a precursor, glucose, by microwave-pyrolysis method. The prepared powders were characterized by scanning electron microscopy （SEM）, X-ray diffraction （XRD）, X-ray fluorescence （XRF） and charge/discharge tests. XRD results indicate that the carbon coating does not change the phase structure of LiNil/3Mnl/3C01/302 material. SEM results show that the surface of spherical carbon-coated material becomes rough. Electrochemical performance results show that the carbon coating can improve the cycling performance of LiNii/3Mnl/3C01/302. The specific discharge capacity retention of the carbon-coated LiNi1/3Mnt/3Col/30z reached 85.0%-96.0% at the 50th cycle at 0.2C rate, and the specific discharge capacity retention is improved at a high rate.

Preparation and thermal conductivity of tungsten coated diamond/copper composites

Tungsten was plated on the surface of diamond by using thermal diffusion method.Different process parameters were employed to prepare the composites with tungsten,diamond and copper.The micro morphology of different samples was observed,and the thermal conductivity of samples was measured by laser flash method.The optimal process parameters for preparing diamond/copper composites with high thermal conductivity were investigated.The results indicated that plating tungsten on diamond could modify the interface bonding.When the diamond was plated for 60 min,the coating appeared intact,uniform and flat,and the thermal conductivity of the sample could reach as high as 486 W/(m·K).The integrity and uniformity were more important than thickness for the coating.When the tungsten-plated diamond was further annealed,the metallurgical bonding between the coating and the diamond was enhanced,and the thermal conductivity rose to 559 W/(m·K).

Cavitation and electrochemical characteristics of thermal spray coating with sealing material

Steel applied in ocean environment is exposed to corrosion and cavitation and is subject to increasing damages. To prevent this, anti-corrosion thermal spray coating technique is widely used. The low-temperature thermal spray coating was performed with 85%Al-14.5%Zn-0.5%Zr for ship materials and various sealing materials were applied to improve its durability, and the electrochemical behavior and cavitation characteristics were observed. The results show that the sealing improves all the properties of the materials. Hybrid ceramic and fluoro-silicon sealing materials show good electrochemical characteristics, and the fluoro-silieon sealing material shows the best anti-cavitation characteristics.

Effects of F-Si sealer on electrochemical characteristics of 15%Al-85%Zn alloy thermal spray coating

Most hulls of the ships are protected with paintings, sacrificial anode, and impressed current cathodic protection methods against corrosion problems. However, these conventional methods are not very effective because the rudder of ships stern are exposed to very severe corrosive environment such as tides, speeds of ships, cavitations and erosion corrosion. The environmental factors such as cavitation and corrosion will cause damage for materials with the shock wave by the creation and destruction of bubble. To solve these problems, the cavitation and electrochemical experiments are executed for thermal spray coating with Al-Zn alloy wire material. Thereafter, and sealed specimens with F-Si sealer on Al-Zn alloy coated specimen are executed to improve electrochemical and anti-cavitation characteristics in sea water. The application of fluorine silicon sealing after spray coating of 15%Al-85%Zn seems to be appropriate not only in static environment but also in dynamic environment.

Effect of thermal cycle on Ni-Cr based nanostructured thermal spray coating in boiler tubes

Ni-Cr based nanostructured feedstock powder was prepared by mechanical milling technique involving repeated welding, fracturing, and re-welding of powder particles in a planetary ball mill. The milled nanocrystalline powders were used to coat carbon steel tubes using high velocity oxygen fuel（HVOF） thermal spraying process. The characterization of the feedstock powder and HVOF coated substrates was performed using optical microscope, X-ray diffractometer（XRD）, scanning electron microscope（SEM）, high resolution transmission electron microscope（HR-TEM）, energy dispersive spectrometer（EDS） and microhardness tests. The coated and uncoated samples were subjected to different thermal cycles and characterized for their phase changes, metallurgical changes and microhardness variations. Ni-Cr nanostructured coated samples exhibited higher mechanical and metallurgical properties compared to their conventionally coated counter parts. The results showed that the nanostructured coating possessed a more uniform and denser microstructure than the conventional coating.

Improved properties of carbon fiber paper as electrode for fuel cell by coating pyrocarbon via CVD method

The fabrication of a pyrocarbon coated carbon paper and its application to the gas diffusion lay(GDL) of proton exchange membrane(PEM) fuel cell were described.This carbon paper was fabricated by using conventional carbon paper as the precursor,and coating it with pyrocarbon by pyrolyzing propylene via the chemical vapor deposition(CVD) method.For comparison,conventional carbon paper composites were also prepared by using PAN-based carbon fiber felt as the precursor followed by impregnation with resin,molding and heat-treatment.SEM characterization indicates that pyrocarbon is uniformly deposited on the surface of the fiber in the pyrocarbon coated carbon paper and made the fibers of carbon felt bind more tightly.In contrast,there are cracks in matrix and debonding of fibers due to carbonization shrinkage in the conventional carbon paper.Property measurements show that the former has much better conductivity and gas permeability than the latter.In addition,current density-voltage performance tests also reveal that the pyrocarbon coating can improve the properties of carbon paper used for electrode materials of fuel cell.

Investigation and Analysis of High Temperature Corrosion and Degradation of Marine Boiler Combustion Swirler

The present paper investigated and analyzed swirler material consisting of mild steel which was subjected to service for the period of one year in a 30 MW marine boiler. Due to the presence of high temperatures in the furnace coupled with the corrosive marine environment swirler material showed accelerated degradation and material wastage. An investigation into the feasibility of manufacturing the existing swirler with an alternate material or coating the swirler material with a thermal barrier coating was undertaken. Based on their properties and performance, SS 304 and SS 316 were proposed as the replacement materials for the swirler. The other alternative of coating the existing swirlers with a form thermal barrier coating to observe for any improvement in their performance at elevated temperatures was also tested. Stellite, which is a Ni-Co based coating, was carried out on the MS samples and the same were exposed to same temperatures mentioned above. The performance of the available options was evaluated with respect to the grain structure of the material, the hardness value of the materials and deterioration at elevated temperatures. Investigation showed the proposed materials/ coatings like SS 304, SS 316 and Stellite coating revealed that SS 316 is the material best suited for high temperature application.

Modification of nano-TiO_2 by Al_2O_3 in-situ coating

A novel technology of in-situ coating Al2O3 on the surface of H4TiO4 was developed to prevent the aggregation of nano-TiO2 powders and improve the dispersibility and thermal stability in the way of forming a uniform coating layer. The heterogeneous nucleation was conducted to prepare the precursor of nano-TiO2 and then Al2O3 was coated on the surface of precursor. The effects of Al2O3 in-situ coating on the properties of nano-TiO2 were investigated. The results show that H4 TiO4 can be dispersed well under alkaline condition （pH 8. 5） and the heterogeneous nucleation can be controlled easily. The optimized uniform coating layer is obtained by adding 5 % （mass fraction ） and 10% of Al2O3 and the aggregation of nano-TiO2 powders is effectively inhibited and the dispersibility is obviously improved. The crystal sizes of TiO2 powders are 12.3, 11.4 and 8. 7 nm after coating 0, 5% and 10% of Al2O3 respectively. Al2O3 on the surface of particulates in amorphous phase could increase the thermal stability of nano-partieles after calcined at 550℃.