Advanced Materials Research Vols. 750-752

Abstract: Two Fe-based alloys , Fe-15Cr-5Ni and Fe-16Cr-7Ni (wt. %), with a small variation in the Ni content were fabricated on a martensitic stainless steel 1Cr13 substrate by laser surface cladding (LSC) using a CO2 laser and Ar shielding gas that was blown into a moten pool. Both LSC alloys exhibited typical rapid directional solidification structures. However, 2 wt% Ni increase led to ~9% increase in the weight fraction of austenite, and ~5% increase in the area proportion of interdendritic regions which contained the higher Cr contents. These microstructural changes caused a great reduction in the microhardness and great improvements in the resistance to electrochemical corrosion in 0.5M H2SO4 solution. The reasons for these differences are discussed in detail.

Abstract: The effect of calendering temperature, speed and linear load on the properties of opacity, brightness, smoothness, paper thickness, gloss and ink absorption of art paper were studied by orthogonal experiment. The art paper coating formulations were as follows: GCC-60 100 pph, solid content 64.6% for precoating; GCC-95 40 pph, Kaolin 60 pph, and solid content 61.3% for top coating. Bar coater was involved to coat by hand in the lab and the coating weight was controlled at 20±2g/m². After calendering in different conditions, the optical properties and printability of paper were analyzed. Regression analysis was used to study which of the calendering conditions was the dominant factor influencing the paper properties. The results showed that linear load was the dominant one, followed by the calendering temperature and calendering speed. After calendering, smoothness and gloss increased, while the brightness and opacity decreased.

Abstract: The compacted even nanonickel film was coated on the surface of cenospheres of the fly ash from coal-burning power plants (3070 μm, particle density 0.3344g/cm³) which are hollow spheres with a shell consisting of quartz and mullite by magnetic sputtering technology. The optical microscope, scanning electric microscope and X-ray diffraction was use to examine the properties and the thickness of the coated nanonickel film. The results show that magnetic sputtering method is efficient to coat smooth, even and tightly combined nanonickel films on the cenospheres surface. The coated cenospheres can be widely used in industries.

Abstract: A Fe-Cr-W-Mo-V overlaying alloy was prepared on Q235 steel by SMAW with different Fe-V powders added in electrode coating. Effects of vanadium on microstructure, hardness and wear resistance of the alloy were studied with SEM, OM, hardness and wear test. The results show that Fe-V powders content affects welding crack number, which increasing quickly at 0-2%(wt, as fellow), decreasing slowly at 2-20%, disappearing above 22%. With the increase of Fe-V, vanadium-rich carbides number increase, the grain size and hardness increase firstly then decrease above 2, at 20% gain the highest. Conversely, the wear loss decreases slowly first, then increases quickly above 2, wear resistance is the best at 20-22%.

Abstract: By vacuum fusion sintering technique made different CeO₂ addition Ni-WC composite coatings on 45 steel. Hardness, wear resistance property and corrosion resistance property of the Rare-earth Ni-WC composite coatings were measured and analyzed by Rockwell hardness tester,micro-hardness tester, friction wear testing machine and Salt spray corrosion box. The results showed that:The CeO₂ content comes up to 0.75% of the coatings` hardness, wear resistance and corrosion resistance property better than those of other coatings.

Abstract: Talc, with different particle sizes, was incorporated to improve flame resistance properties of UV-curable talc/acrylate composite flam-retardant coating at different contents via mechanical blending. Hardness, transmittance, haze, cross-cut adhesion and abrasion resistance results showed that the mechanical and thermal properties of the coatings improved effectively with no comprising on optical properties by adding Talc. The flame retardancy of the UV-curable coatings was investigated by thermogravimetric analysis (TGA) and Microscale Combustion Calorimeter (MCC). The results showed that the incorporation of Talc into the organic network led to an improvement in the thermal stability and flame retardancy of the coating materials. When talc content increased from 0 to 30 wt%, the peak heat release rate (PHRR) decreased from 191.1 W/g to 130.6 W/g, and the total heat release(THR) droped from 17.0 kJ/g to 11.1 kJ/g.

Abstract: Coating of ME20M magnesium alloys was first carried out using electroless nickel plating technique with an environmentally-friendly pretreatment. The morphology and specific weight loss of the pickling process were investigated. The Ni-P coating was characterized by its structure, morphology, chemical composition, adhesion strength and corrosion resistance. The SEM image shows that the pyrophosphate pickling process can produce a rough surface and the thermal shock test indicates excellent adhesion strength between magnesium alloys and Ni-P coating. The damp heat test and electrochemical measurement prove the Ni-P coating significantly increase the corrosion resistance of ME20M magnesium alloys.

Abstract: Nickel-coated aluminum powders used as conductive fillers were prepared with different stabilizers added in electroless plating bath. Their Electrical conductivity and magnetoconductivity were measured to evaluate the effect of stabilizers on Nickel-coated aluminum powders. The results suggested that the electrical conductivity of Ni-coated aluminum powder was dependent on the variety and content of stabilizers while the magnetoconductivity was irrelevant to the stabilizers. It was proved that the concentration and variety of stabilizer had different influence on the microstructure of coating and changed the electrical conductivity of Ni-coated aluminum powder thereby.

Abstract: Based on laser irradiation processing experiment for repairing damaged copper thin film specimens, the effect of temperature field induced by pulsed laser surface irradiation on fatigue damage repairing of copper thin film was studied by numerical simulation method. First the temperature field of copper thin film after laser irradiation was analyzed by ANSYS under different pulse energies and pulse numbers. Then the surface morphologies of copper thin film specimens were observed by optical microscope before and after laser surface irradiation. The results showed that laser irradiation processing has a better effect on fatigue damage repairing when the temperature induced by laser surface irradiation reaches about 1200 °C. A slightly melted morphology on the surface of copper thin film was observed in this case. In addition, except for the full healing of fatigue damage, the total fatigue life was increased about 2 times at the nominal stress level of 120MPa.

Abstract: Based on SiC aggregate, SiC powder and ultra-fine SiC powder as the main starting materials and B₄C as additive, the newly-developed self-bonded SiC material was pressed and fired at 2200°C for 10 hours in Ar environment in the high-temperature furnace. The phase composition and microstructure were investigated. In the paper, traditional self-bonded SiC material and Si3N4-bonded SiC material were taken for comparison with the newly-developed self-bonded SiC material in terms of strength, thermal conductivity, cryolite resistance, molten alkali resistance and oxidation resistance etc. The results show that the newly-developed self-bonded SiC material contains 98.42% α-SiC and presents obvious higher thermal conductivity than traditional self-bonded SiC material and much better cryolite resistance, molten alkali resistance and oxidation resistance than traditional self-bonded SiC and Si3N4-bonded SiC materials.