渗铜法制备抗菌不锈钢工艺及组织性能的研究

采用膏剂渗铜法制备18-8型抗菌不锈钢,研究了膏剂配方、渗铜工艺对18-8型不锈钢组织和性能的影响。结果表明,不锈钢采用60%CuO＋7%Na3AlF3＋33%Al2O3或75%CuO＋7%Na3AlF3＋18%Al2O3膏剂,900℃×8h加热后缓冷的表层组织为典型的岛状组织,Cu主要分布于岛状组织的边缘;渗铜层硬度略大于心部,并且具有优良的抗菌性能,杀菌率可达99.99%。     

沉积扩散法制备不锈钢抗菌渗铜层的研究

采用沉积扩散法在0Cr18Ni9奥氏体不锈钢和2Cr13马氏体不锈钢表面制备抗菌渗铜层，讨论了不同的扩散工艺参数对这两种不锈钢抗菌渗铜层抗菌性能和抗菌持久性的影响。用小角度X射线衍射(GXRD)分析了渗铜层的相组成。研究结果表明，用沉积扩散法在不锈钢表层制备含ε-Cu相的抗菌渗铜层，其对大肠杆菌和黄色葡萄球菌具有良好的抗菌性能。     

渗铜法制备抗菌不锈钢渗层工艺的研究

使用自制的渗铜剂在奥氏体不锈钢 0Cr18Ni9表面获得≥ 5 0 μm深度的抗菌层。研究了渗铜工艺对渗层的影响 ,获得了最佳热处理工艺为 90 0℃× 8h缓慢冷却。研究表明获得的渗层具有良好的抗菌性能。     

AISI304不锈钢渗铜后的微观组织及抗菌性能

以CuO＋NH4Cl为渗剂对AISI 304不锈钢表面进行化学渗铜处理，获得了具有优良抗菌性能的渗铜层。用扫描电镜及小掠射X射线衍射仪分析了渗层深度、微观组织及相组成。试验结果表明，当渗铜处理温度大于900℃后，渗铜层深度及渗层中富铜相Cu9.9Fe0.1及Cu3.8Ni的生成量快速增加。渗层中富铜相生成量越多，不锈钢的抗菌效果越佳，尤其是金黄色葡萄球菌。AISI304不锈钢经950℃保温4h渗铜处理后得到了较深的渗铜层，铜以富铜相形式均匀分布于渗层，具有优良的抗大肠杆菌和金黄色葡萄球菌的效果。     

304不锈钢双辉等离子渗铜铪表面合金层组织及抗菌性能

利用双辉渗金属技术在304不锈钢表面进行铜铪共渗,使用光学显微镜、X射线衍射仪和扫描电镜研究铜铪共渗合金层的显微组织、相结构、形貌、成分和表面硬度,采用薄膜密贴法对合金层进行抗菌性能的检测。结果表明:铜铪共渗合金层由扩散层和沉积层构成,合金层表面组织致密、分布连续、无明显裂纹和孔隙。铜、铪含量由表至里逐渐减少,渗铜铪试样中的铬和碳都出现向渗层表面迁移的现象。抗菌检测中,铜铪合金层表面对大肠杆菌和金黄色葡萄球菌都具有优良的抗菌性能,抗菌率均达到99%以上。当铜在源极棒中比例达到80%和90%时,所得到的渗铜铪试样抗菌率分别为99.83%和99.12%,当铜比例为70%时得到渗后试样的抗菌率仅为93%。渗后试样表面硬度约为605 HV0.1,大于渗铜试样和304不锈钢表面硬度。     

热处理对含铜3Cr13马氏体不锈钢抗菌性能的影响

研究了抗菌热处理对含铜 3Cr13不锈钢组织和抗菌性能的影响。试验表明抗菌热处理是其获得优异抗菌性能的关键。粘结薄膜法显示抗菌热处理后的 0 35C 13Cr 2 6 8Cu马氏体不锈钢对金黄色葡萄球菌和大肠杆菌的抗菌率 >99%。试验确定了最佳热处理参数 ,并从理论上分析了抗菌机理     

含铜抗菌不锈钢的抗菌特性研究

研究了铁素体和奥氏体含铜抗菌不锈钢的抗菌特性及相关机制.实验结果表明,含铜抗菌不锈钢具有优良的广谱杀菌作用,对本文选择的大部分革兰氏阴性菌(G-)和革兰氏阳性菌(G )的杀灭率均在99.0%以上.通过铁素体抗菌不锈钢对大肠杆菌作用不同时间的研究证明,抗菌不锈钢的杀菌率和其与细菌作用时间有关,铁素体抗菌不锈钢与大肠杆菌作用150 min左右时间后的杀菌率才会达到99.9%的最大值.原子力显微镜的观察表明,抗菌不锈钢对大肠杆菌的杀灭表现为菌体内大量物质流失,细菌出现干瘪现象.电化学实验结果表明,抗菌不锈钢与大肠杆菌作用后,会由于其表面抗菌相中铜离子溶出的加快,而表现为其耐点蚀电位的下降.     

304不锈钢双辉渗铜铈渗层结构分析及其抗菌性能

用双辉等离子技术结合空心阴极效应将铜铈元素渗入304不锈钢。用金相显微镜、扫描电镜、能谱分析仪、X射线衍射仪等方法研究了被渗试样的组织结构,解释了渗层分为白亮层和渗层暗带以及碳元素和铬元素向渗层表层偏聚以及其他元素分布发生变化的原因。对渗后试样进行抗菌实验。结果表明,渗后不锈钢对大肠杆菌和金黄色葡萄球菌具有良好的抗菌性能。     

304不锈钢表面Ag-Cu渗镀层的耐蚀及抗菌性能研究

采用双辉技术和化学镀法在304不锈钢表面制备Ag-Cu渗镀改性层,并对其耐蚀及抗菌性进行了研究分析。结果表明:渗镀层具有良好的耐蚀性,且与基材结合良好;与渗Cu不锈钢和不锈钢基材相比,抗菌性能明显改善,灭菌率达100%。     

马氏体抗菌不锈钢的微观组织及其抗菌性能

含Cu马氏体抗菌不锈钢经特殊的抗菌热处理析出ε-Cu相,采用覆膜法研究其抗菌性能.实验结果表明:马氏体抗菌不锈钢对大肠杆菌和金黄色葡萄球菌易于杀灭;鼠伤寒杆菌需要一定时间杀灭;白色念株菌需要较长时间杀灭.这与细菌的细胞壁组织结构、细胞壁厚度和其属性有关.抗菌不锈钢对细胞壁较薄、肽聚糖含量较低、组织疏松、金属离子易穿透细胞壁的细菌易于杀灭;反之,细菌不易于杀灭.随着抗菌作用时间的延长,铜离子浓度的提高,抗菌不锈钢的杀菌效力显著提高.马氏体抗菌不锈钢经表面打磨或磨损仍然具有相同的抗菌性能.     

Rheology Feature of Simple Metal Melt

The rheology feature of Sb, Bi melt and alloys was studied using coaxial cylinder high-temperature viscometer. The results showed that the curve of torsion-rotational speed for Sb melt presents a linear relation in all measured temperature ranges, whereas for the Bi melt, the curve presents obvious non-Newtonian feature within the low temperature range and at relative high shear stress. The rheology feature of Sb80Bi20 and Sb20Bi80 alloy melts was well correlated with that of Sb and Bi, respectively. It is considered that the rheology behavior of Sb melt plays a crucial role in Sb80Bi20 alloy and that of Bi melt plays a crucial role in Sb20Bi80 alloy.     

Microstructures and Mechanical Properties of a Newly Developed Austenitic Heat Resistant Steel

The effect of heat treatment on the microstructures and mechanical properties of a newly developed austenitic heat resistant steel(named as T8 alloy) for ultra-supercritical applications have been studied. Results show that the main phases in the alloy after solution treatment are γ and primary MX. Subsequent aging treatment causes the precipitation of M_(23)C_6 carbides along the grain boundaries and a small number of nanoscale MX inside the grains. In addition, with increasing the aging temperature and time, the morphology of M_(23)C_6 carbides changes from semi-continuous chain to continuous network.Compared with a commercial HR3C alloy, T8 alloy has comparable tensile strength, but higher stress rupture strength. The dominant cracking mechanism of the alloy during tensile test at room temperature is transgranular, while at high temperature, intergranular cracking becomes the main cracking mode, which may be caused by the precipitation of continuous M_(23)C_6 carbides along the grain boundaries. Typical intergranular cracking is the dominant cracking mode of the alloy at all stress rupture tests.     

The 15th Global Foundry Sourcing Conference 2014held in Qingdao China

Organized by Suppliers China Co., Ltd and co-organized by the National Technical Committee 54 on Foundry of Standardization Administration of China, the 15th Global Foundry Sourcing Conference 2014 （hereinafter referred to as FSC 2014） was successfully held on Sep. 23rd in Grand Regency Hotel, Qingdao. More than 500 delegates from home and abroad attended this conference, including over 130 purchasers from 20 countries and 380 domestic and foreign suppliers.     

Secondary Recrystallization Behaviors of Grain-Oriented 6.5 wt% Silicon Steel Sheets Produced by Rolling and Nitriding Processes

By rolling and nitriding processes, 0.23- to 0.3-mm-thick grain-oriented 6.5 wt% silicon steel sheets were produced. The core losses of grain-oriented 6.5 wt% silicon steel at frequencies ranging from 400 Hz to 20 k Hz were lower than that of the grain-oriented 3 wt% silicon steel with the same thickness by 16.6–35.8%. The secondary recrystallization behavior was investigated by scanning electron microscopy, energy-dispersive spectroscopy, and electron backscattered diffraction. The results show that the secondary recrystallization in high-silicon steel sheets develops more completely as the nitrogen content increases after nitriding, secondary recrystallized grain sizes become larger, and the sharpness of Goss texture increases. Because more {110}116 grains in the subsurface and the central layer of the sheets have a lot of 20°–45° high-energy boundaries in addition to Goss grains, {110}116 can be the main component through selective growth during secondary recrystallization when the inhibitor quantity is not enough and inhibitor intensity is weaker. The increases in nitrogen content can increase the inhibitor intensity and hinder abnormal growth of a mount of {110}116 grains and therefore enhance the sharpness of Goss texture.     

Laser Cladded TiCN Coatings on the Surface of Titanium

Laser cladded coatings of TiCN were produced on the surface of titanium. To obtain the optimal techniques, several conditions were tested by varying the laser scanning rate. The choice of shielding gas was also studied. The cladded coatings were then evaluated from the surface mechanics point of view based on their microhardness. The microstructure of some interesting samples was investigated by optical micrographs (OM). The results showed that under the condition of fixed pulse frequency and pulse width, the laser scanning rate and the shielding gas are the main factors influencing the components of coatings. TiCN coatings were decompounded and oxidized during the cladding process in the condition of no shielding gas of N2. X-ray diffraction results indicated that the composite coatings composed of TiCN, TiC, Ti2N, and TiO2 were produced using appropriate techniques. The results indicated that the best condition in terms of the surface microhardness is obtained when the scanning rate is 1.5mm / s, the pulse frequency is 15Hz, the pulse width is 3.0ms, and N2 is chosen as the shielding gas. The microhardness of the composite coatings is about 1331kg · mm - 2, which is about 4 times that of the substrate. The optical micrographs indicated that the cladding zone is made up of TiCN, TiO2, and some interdendritic Ti, but the diffusion zone mainly consists of the dendrites phase, and the cladded depth is about 80?滋m, which is more than 2 times that of the laser nitrided sample. There were no microcracks or air bubbles in the cladded sample, which was cladded using the above optimal techniques.     

Microstructure and Mechanical Properties of X80 Pipeline Steel Joints by Friction Stir Welding Under Various Cooling Conditions

X80 pipeline steel plates were friction stir welded(FSW) under air, water, liquid CO_2 + water, and liquid CO_2 cooling conditions, producing defect-free welds. The microstructural evolution and mechanical properties of these FSW joints were studied. Coarse granular bainite was observed in the nugget zone(NZ) under air cooling, and lath bainite and lath martensite increased signifi cantly as the cooling medium temperature reduced. In particular, under the liquid CO_2 cooling condition, a dual phase structure of lath martensite and fi ne ferrite appeared in the NZ. Compared to the case under air cooling, a strong shear texture was identifi ed in the NZs under other rapid cooling conditions, because the partial deformation at elevated temperature was retained through higher cooling rates. Under liquid CO_2 cooling, the highest transverse tensile strength and elongation of the joint reached 92% and 82% of those of the basal metal(BM), respectively, due to the weak tempering softening. A maximum impact energy of up to 93% of that of the BM was obtained in the NZ under liquid CO_2 cooling, which was attributed to the operation of the dual phase of lath martensite and fi ne ferrite.     

INDUSTRY NEWS

China Securities News reported on March 21, 2014： Guangdong Hongtu Wuhan Die Casting Co., Ltd. （Wuhan Hongtu）, a wholly owned subsidiary of Guangdong Hongtu Technology （Holdings） Co., Ltd., held a groundbreaking ceremony recently. With the registered capital of 50 million Yuan, Wuhan Hongtu has a total land area of 100,000 square meters and a plant construction area of 72,000 square meters. It is expected to have a production capacity of about 30,000 tonnes of aluminum castings annually after it is put into production.     

Microstructure,Mechanical Properties and Corrosion Behavior of Extruded Mg–Zn–Ag Alloys with Single-Phase Structure

Mg–Zn–Ag alloys have been extensively studied in recent years for potential biodegradable implants due to their unique mechanical properties,biodegradability and biocompatibility.In the present study,Mg–3Zn-x Ag(wt%,x=0.2,0.5 and0.8)alloys with single-phase crystal structure were prepared by backward extrusion at 340°C.The addition of Ag element into Mg–3Zn slightly influences the ultimate tensile strength and microstructure,but the elongation firstly increases from12%to 19.8%and then decreases from 19.8%to 9.9%with the increment of Ag concentration.The tensile yield strength,ultimate tensile strength and elongation of Mg–3Zn–0.2Ag alloy reach up to 142,234 MPa and 19.8%,respectively,which are the best mechanical performance of Mg–Zn–Ag alloys in the present work.The extruded Mg–3Zn–0.2Ag alloy also possesses the best corrosion behavior with the corresponding corrosion rate of 3.2 mm/year in immersion test,which could be explained by the single-phase and uniformly distributed grain structure,and the fewer twinning.     

Growth Morphologies of a Binary Alloy with Low Anisotropy in Directional Solidification

Two new classes of growth morphologies, called doublons and seaweed, were simulated using a phase-field method. The evolution of doublon and seaweed morphologies was obtained in directional solidification. The influence of orientation and velocity on the growth morphology was investigated. It was indicated that doublons preferred growing with its crystallographic axis aligned with the heat flow direction. Seaweed, on the other hand, could be obtained by tilting the crystalline axis to 45°. Stable doublons could only exist in a range of velocity regime. Beyond this regime the patterns formed would be unstable. The simulation results agreed with the reported experimental results qualitatively.