Chen Wang

Optical Properties Characterization of Thermoplastics Used in Laser Transmission Welding: Scattering and Absorbance

A better understanding of the optical properties of plastics at IR wavelengths is important for optimizing the laser transmission welding process. In this study, the optical properties, scattering and absorbance, of polypropylene (PP), polycarbonate (PC) and polyamide (PA) were investigated by using spectrophotometer with integrating sphere. The influence of thickness, surface roughness and filler content on optical properties of thermoplastics was evaluated. The results could contribute to a better understanding of the process itself and to success in the practical applications.

Effect of Defocus Distance on Layer Quality in Insider-Laser Coaxial Powder Feeding Laser Cladding

Insider-laser coaxial powder feeding laser cladding is one kind of technique, which can be used in metal part directly manufacturing field. Compared with outsider-laser coaxial powder feeding laser cladding techniques, it has significant advantages [1]. In order to research the effect of defocus distance on the layer quality in insider-laser coaxial powder feeding laser cladding, it has taken some expriments in this paper to study the layer quality by constantly changing the defocus distance, with other laser cladding process parameters invariable. In addition, this paper measues, analysis the cladding layer’s width, height, the surface quality (including surface flatness, flat-wide ratio and flat-high ratio [2]), hardness and microstructure, then summarizes the effect of the defocus distance on the layer quality in this paper.

Preparation of Borosilicate Xerogel and Research on its Mineralization

Tributyl borate was first adopted for the introduction of boron in the preparation of bioactive borosilicate xerogel by sol-gel method. The xerogel reacted continuously in 0.25M K2HPO4 solution with a starting pH value of 7.0 at 37 °C for 1day. The structural, morphologies and compositional changes resulting from the conversion were characterized using X-ray diffraction, scanning electron microscopy and Fourier transform infrared spectroscopy. The results indicated that speed of formation of HA was cut way back on the time with the addition of boron and the induction period for the HA nucleation on the surface of the borosilicate xerogel was short than 1 days. The conversion mechanism of the borosilicate xerogels to hydroxyapaptite was also discussed.

Microscopic Mechanism Research of T10 Steel Accumulated Plastic Deformation in Low Stress Load

The influence of static load and impact load in the same value of low stress on microstructure and micro-strain of T10 steel specimens is studied. The results show that softening and hardening phenomenon of Specimen appears alternately in the process of being loaded. Hardness value will tend to stable when loading time or impact times increase to a certain value. Compared to impact load，static load has a more well-distributed、pyknotic microstructure and a smaller variable quantity of microscopic strain.

Study on Behavior of Ni-Based and Fe-Based Hardfacing Alloys in Plant Valves with Laser Cladding

Two new kinds of Ni-based and Fe-based alloy power have been developed. Both kinds of power have been successfully coated by laser cladding on the surface of stainless steel as strengthening layers. The morphology and microstructure of these coatings have been analyzed by SEM and XRD, the mircohardness, wear and corrosion resistance of Ni-based and Fe-based laser cladding coatings have been measured respectively. The analysis reveals that both coatings with smooth and successive surfaces and homogeneous morphology have been obtained under the proper laser processing parameters; besides, Ni-based and Fe-based coatings have fine, well-proportioned and dense microstructure, and better joints with the substrates, respectively. So the results indicate that Ni-based and Fe-based alloys can supersede the cobalt-based alloys in the certain conditions.

Study on the Effects of Process Parameters on Weld Joint using Coaxial Inside-Beam Wire Feeding

The effects of process parameters such as laser power, scanning velocity and wire feeding speed on weld joint quality has been discussed through some laser welding experiments using coaxial inside-beam wire feeding process method. The results reveal that: Along with the increase of the laser power, weld width and depth are increasing gradually; Coating surface will appear burning loss and deboss when laser power is too large. The increase of scanning velocity decreases the depth and width of molten bath, and abates laser hole-effect, so the metal plate can not be welded penetration. Larger wire feeding speed can avoid welding seam produce burning loss, but it also can strengthen welding wire reflect the laser, and decline the welding.

Study of Good Yield and Efficiency in TFT-LCD Module Process

This paper introduces the TFT-LCD (Tablet Film Transistor Liquid Crystal Displayer) module process that is composed by two stages, JI (JISO) process and MA (Module Assy) process. In JI process, the main defect phenomena are bonding particle and bonding defect, which have a bad effect on the product yield. In MA process, the key factor of the output is the inequality workload to every worker and unbalance of the production line. With the solution of plasma cleaning and pressure diversification, the bonding defect ratio descent from 0.34% to 0.14%. By making workload balance, the efficiency of MA process has been increased.