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RISS 인기검색어
- 검색키워드
- 저자 : Qingliang Chen (검색결과 4 건)
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Grinding Damage of BK7 using Copper-Resin Bond Coarse-Grained Diamond Wheel
Qingliang Zhao,Junyun Chen,Haitao Huang,Xiaoyan Fang 한국정밀공학회 2011 International Journal of Precision Engineering and Vol. No.
Coarse-grained wheels can realize high efficient grinding of optical glass. However, the serious surface and subsurface damage will be inevitably introduced by the coarse-grained wheels. In this paper, the grinding damage of a copper-resin bond coarse-grained diamond wheel with grain size of 150μm was investigated on optical glass BK7. The wheel was first properly trued with a metal bond diamond wheel, then pre-dressing for the wheel and grinding experiments are carried out on a precision grinder assisted with electrolytic in process dressing (ELID) method. The surface roughness (Ra) of ground surface was measured using an atomic force microscope (AFM) and the surface topography were imaged by a white light interferometer (WLI) and the AFM. The subsurface damage level of ground surface was evaluated by means of both MRF spot method and taper polishing-etching method, in term of the biggest depth of subsurface damage, distribution of micro defects beneath the ground surface, the cluster depth of subsurface damage, relationship between subsurface damage (SSD)and PV surface roughness (SR), propagating distance and pattern of cracks beneath the ground surface. Experimental results indicate that a well conditioned copper-resin bond coarse-grained diamond wheel on a precision grinder can generate good surface quality of Ra less than 50nm and good subsurface integrity with SSD depth less than 3.5μm for optical glass BK7.
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Grinding Marks on Ultra-Precision Grinding Spherical and Aspheric Surfaces
Bing Chen,Bing Guo,Shichun Li,Zhaohui Deng,Qingliang Zhao 한국정밀공학회 2017 International Journal of Precision Engineering and Vol.4 No.4
Grinding marks are regard as a great obstacle to manufacture spherical and aspheric surfaces with higher surface quality, lower energy and wastage. The scallop-height was studied for optimizing the grinding parameters firstly to reduce its effect on grinding marks. Secondly, the expression of grinding points distribution was established to characterize the grinding marks caused by the radial run-out of grinding wheel. And then, the aspheric grinding experiments of monocrystalline silicon were carried out to investigate the influence of grinding marks on surface quality. The experiments revealed that the remarkable grinding marks with patterned grinding points distribution would cause more fractures and roughness, deeper grooves, and more inhomogeneous surface quality compared with the weak grinding marks. The discriminating standard of grinding marks was established, and the grinding parameters were optimized for homogenizing the grinding points distribution by this discriminating standard to reduce the grinding marks in actual grinding process. Finally, the large size infrared lens was ground with high surface quality by the optimized grinding parameters, and the results of surface quality demonstrate that the discriminating standard was effective. This research provides references and ideas for grinding aspherical surface with high surface quality and efficiency, low energy and wastage.
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Immobilized Bioactive Agents onto Polyurethane Surface with Heparin and Phosphorylcholine Group
Mingqi Tan,Yakai Feng,Heyun Wang,Li Zhang,Musammir Khan,Jintang Guo,Qingliang Chen,Jianshi Liu 한국고분자학회 2013 Macromolecular Research Vol.21 No.5
Heparin (HEP) and phosphorylcholine groups (PC) were grafted onto the polyurethane (PU) surface in order to improve biocompatibility and anticoagulant activity. After the surface grafting sites of PU were amplified with the primary amine groups of polyethylenimine (PEI), heparin was covalently linked onto the surface by the reaction between the amino group and the carboxyl group. PC groups were covalently immobilized on the PU-PEI surface through the reaction between the amino group and the aldehyde group of phosphorylcholine glyceraldehyde (PCGA). The surface density of primary amine groups was determined by a ninhydrin assay. The amino group density reached a maximum of 0.88 μmol/cm2 upon incorporation of 10 wt% PEI. The amount of heparin covalently immobilized on the PU-PEI surface was determined by the toluidine blue method. The grafting chemistry resulted in the comparatively dense immobilization of HEP (2.6 μg/cm2) and PC to the PU-PEI surfaces. The HEP and PC modified surfaces were characterized by water uptake (PU 0.15 mg/cm2, PU-PEI 3.54 mg/cm2, PU-HEP 2.04 mg/cm2, PU-PC 2.38 mg/cm2), water contact angle (PU 95.3º, PU-PEI 34.0º, PU-HEP 39.5º, PU-PC 37.2º), attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR), X-ray photoelectron spectroscopy (XPS),atomic force microscopy (AFM), and scanning electron microscope (SEM). The results demonstrated that the PUPEI surface was successfully grafted with HEP and PC. The hydrophilicity and hemocompatibility of these grafted surfaces were significantly improved. These results suggested that the PU-HEP and PU-PC composite films are promising candidates for blood contacting tissue engineering.
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