Influence of mechanical excitation on adsorption of sodium diethylamino dithio-formate on galena and sphalerite

1　ＩＮＴＲＯＤＵＣＴＩＯＮＮｕｍｅｒｏｕｓｉｎｖｅｓｔｉｇａｔｉｏｎｓｈａｖｅｓｈｏｗｎｔｈａｔｔｈｅｍｅｃｈａｎｉｃａｌａｃｔｉｏｎｃａｎｅｆｆｅｃｔｉｖｅｌｙｃｈａｎｇｅｔｈｅｓｔａｔｅｏｆａｍａｔｅｒｉａｌ,ｃａｔａｌｙｚｅｓｏｍｅｃｈｅｍｉｃａｌｒｅａｃｔｉｏｎｓ ,ｂｒｉｎｇａｂｏｕｔｓｏｍｅｃｈｅｍｉｃａｌｃｏｎｖｅｒｓｉｏｎｓａｎｄｃｏｎｓｉｄｅｒａｂｌｙａｃ ｃｅｌｅｒａｔｅｍｕｌｔｉｐｈａｓｅｐｒｏｃｅｓｓｅｓ .Ｈｏｗｅｖｅｒ,ｔｈｉｓｋｉｎｄｏｆｒｅｓｅａｒｃｈｗａｓｍｏｓｔｌｙ…     

METHOD FOR CALCULATION AND SIMULATION ON PROPAGATION OF SURFACE CRACK ON SPHERICAL VESSELS MADE OF STEELS

１．ＩｎｔｒｏｄｕｃｔｉｏｎＴｈｅｍｅｔｈｏｄｏｆｅｖａｌｕａｔｉｎｇｔｈｅｆｌａｗｓｏｎｐｒｅｓｓｕｒｅｖｅｓｓｅｌｓｗｉｔｈｔｈｅａｉｄｏｆｔｈｅｔｈｅｏｒｙｏｆｆｒａｃｔｕｒｅｍｅｃｈａｎｉｃｓｈａｓｂｅｅｎｗｉｄｅｌｙａｃｃｅｐｔｅｄｏｖｅｒｔｈｅｗｏｒｌｄ．Ｉｔｓｈｏｕｌｄｃｏｎｓｉｄｅｒｔｈｅｃｈａｒａｃｔｅｒｉｓｔｉｃｓｏｆｔｈｅｖｅｓｓｅｌ,ｓｕｃｈａｓｔｈｅｔｏｕｇｈｎｅｓｓｏｆｔｈｅｍａｔｅｒｉａｌ,ｔｈｅｓｉｚｅ（ｅｓｐｅｃｉａｌｌｙｔｈｅｔｈｉｃｋｎｅｓｓ）ｏｆｔｈｅｗ…     

FORMING OF PARTICLES REINFORCED METAL MATRIX COMPOSITES bYCASTING UNDER COUNTER GRAVITY

１．ＩｎｔｒｏｄｕｃｔｉｏｎＴｈｅｍａｎｕｆａｃｔｕｒｉｎｇｐｒｏｃｅｓｓｅｓｏｆｐａｒｔｉｃｌｅｓｒｅｉｎｆｏｒｃｅｄｍｅｔａｌｍａｔｒｉｘｃｏｍｐｏｓｉｔｅｓｍａｉｎｌｙｉｎｃｌｕｄｅｐｏｗｄｅｒｍｅｔａｌｌｕｒｇｙ,ｓｐｒａｙｃａｓｔｉｎｇ,ｌｉｑｕｉｄｐｅｎｅｔｒａｔｉｏｎｗｉｔｈｐｒｅｓｓｕｒｅｏｒｗｉｔｈｏｕｔｐｒｅｓｓｕｒｅａｎｄｓｔｉｒｒｉｎｇｃａｓｔｉｎｇａｎｄｓｏｏｎ．Ｓｔｉｒｒｉｎｇｃａｓｔｉｎｇｉｓａｐｏｔｅｎｔｉａｌｐｒｏｃｅｓｓｂｅｃａｕｓｅｉｔｉｓｏｆｌｏｗｃｏｓｔ…     

Study on morphologies and structures of diamond films synthesized on cemented carbide substrates

１ＩｎｔｒｏｄｕｃｔｉｏｎＴｈｅｒｅａｒｅａｌｏｔｏｆｎｏｎｍｅｔａｌｌｉｃｍａｔｅｒｉａｌｓｓｕｃｈａｓｃｅｒａｍｉｃｓ,ｆｉｂｅｒｒｅｉｎｆｏｒｃｅｄｐｌａｓｔｉｃｓａｎｄｖａｒｉｏｕｓｗｏｏｄｂａｓｅｄｐｒｏｄｕｃｔｓ,ｎｏｎｆｅｒｒｏｕｓｍｅｔａｌｓａｎｄａｌｌｏｙｓ,ａｎｄｃｏｍｐｏｓｉｔｅｓｗｈｉｃｈｃａｎｎｏｔｂｅｍａｃｈｉｎｅｄｕｓｉｎｇｃｅｍｅｎｔｅｄｃａｒｂｉｄｅｃｕｔｔｉｎｇｔｏｏｌｓ．Ｗｉｔｈｔｈｅｃｏｎｔｉｎｕａｌｄｅｖｅｌｏｐｍｅｎｔｓａｎｄｅｎｇｉｎｅ…     

A STUDY OF FATIGUE WEAR PERFOR MANCE OF TiN COATED SURFACE BY PHYSICAL VAPOR DEPOSITION

１．ＩｎｔｒｏｄｕｃｔｉｏｎＲｏｌｌｉｎｇｃｏｎｔａｃｔｆａｔｉｇｕｅｗｅａｒｉｓａｐｈｅｎｏｍｅｎｏｎｏｆｇｒｅａｔｐｒａｃｔｉｃａｌｓｉｇｎｉｆｉｃａｎｃｅｔｏｍａｎｙｅｎｇｉｎｅｅｒｉｎｇａｐｐｌｉｃａｔｉｏｎｓｉｎｖｏｌｖｉｎｇｃｏｎｃｅｎｔｒａｔｅｄｃｏｎｔａｃｔｓ．Ｉｎｓｕｃｈｓｉｔｕａｔｉｏｎｓ,ａｆｅａｓｉｂｌｅｓｏｌｕｔｉｏｎｉｓｓｕｒｆａｃｅｔｒｅａｔｍｅｎｔｏｎｏｎｅｏｒｂｏｔｈｏｆｒｏｌｌｉｎｇｃｏｍｐｏｎｅｎｔｓｔｏｉｍｐｒｏｖｅｉｔｓｆａｔｉｇｕｅｗｅａｒｐｅｒｆ…     

Electric arc furnace dust non-isothermal reduction kinetics

1　ＩＮＴＲＯＤＵＣＴＩＯＮＴｈｅａｉｒｂｏｒｎｅｆｉｎｅｐａｒｔｉｃｕｌａｔｅＥｌｅｃｔｒｉｃＡｒｃＦｕｒ ｎａｃｅ (ＥＡＦ)ｄｕｓｔｉｓｇｅｎｅｒａｔｅｄｉｎｔｈｅｓｔｅｅｌｍａｎｕｆａｃｔｕｒ ｉｎｇｐｒｏｃｅｓｓｗｈｅｎｓｃｒａｐｉｓｅｌｅｃｔｒｉｃａｌｌｙｍｅｌｔｅｄ .Ｉｔｉｓｃｏｎｓｉｄｅｒｅｄａｓａｈａｚａｒｄｏｕｓｗａｓｔｅｂｅｃａｕｓｅｏｆｌｅａｃｈｉｎｇｃｈａｒａｃｔｅｒｉｓｔｉｃｏｆｈｅａｖｙｍｅｔａｌｓｓｕｃｈａｓｌｅａｄ ,ｚｉｎｃａｎｄｃｈｒｏｍｉｕｍ ,ｗｈｉｃｈａｒｅ ｐ…     

Twinning induced plasticity in commercially pure titanium at low temperature

1　ＩＮＴＲＯＤＵＣＴＩＯＮＰｕｒｅｔｉｔａｎｉｕｍｉｓｕｓｅｄｗｉｄｅｌｙｉｎ ｐｏｗｅｒｓｔａｔｉｏｎｓａｎｄｃｈｅｍｉｃａｌｐｌａｎｔｓｂｅｃａｕｓｅｏｆｉｔｓｅｘｃｅｌｌｅｎｔｐｈｙｓｉｃａｌ,ｃｈｅｍｉｃａｌａｎｄｍｅｃｈａｎｉｃａｌｂｅｈａｖｉｏｒｓ .Ｔｈｅａｂｓｅｎｃｅｏｆａｄｕｃｔｉｌｅ ｂｒｉｔｔｌｅｔｒａｎｓｉｔｉｏｎｉｎｐｕｒｅｔｉｔａｎｉｕｍｒｅｓｕｌｔｓｉｎｓａｔｉｓｆａｃｔｏｒｙｓｔｒｅｎｇｔｈａｎｄｄｕｃｔｉｌｉｔｙａｔｃｒｙｏｇｅｎｉｃｔｅｍ ｐｅｒａｔｕｒｅ .Ｔｈｅ…     

Gold leaching with elemental sulfur in alkaline solutions under oxygen pressure

1　ＩＮＴＲＯＤＵＣＴＩＯＮＣｙａｎｉｄａｔｉｏｎｐｒｏｃｅｓｓ ,ｃｈａｒａｃｔｅｒｉｚｅｄｂｙｅｆｆｅｃｔｉｖｅｎｅｓｓａｎｄｌｏｗｏｐｅｒａｔｉｎｇｃｏｓｔ,ａｓａｃｏｎｖｅｎｔｉｏｎａｌｔｅｃｈｎｏｌｏｇｙｆｏｒｇｏｌｄｅｘｔｒａｃｔｉｏｎｆｒｏｍｏｒｅｓ ,ｈａｓｂｅｅｎｕｓｅｄｉｎｉｎｄｕｓｔｒｙｆｏｒｏｖｅｒ 10 0ｙｅａｒｓ .Ｈｏｗｅｖｅｒｔｈｅｃｙａｎｉｄｅｉｓａｈｉｇｈｌｙｔｏｘｉｃｃｈｅｍｉｃａｌ,ａｎｄｃｏｍｍｅｒｃｉａｌｃｙａｎｉｄａｔｉｏｎｐｒｏｃｅｓｓｉｓｌｉｍｉｔｅｄｉｎｔ…     

Prediction of thermodynamic properties for multicomponent system with Chou model

1　ＩＮＴＲＯＤＵＣＴＩＯＮＴｈｅｇｒｏｕｐＩＩＩ Ｖｃｏｍｐｏｕｎｄｓｅｍｉｃｏｎｄｕｃｔｏｒｓａｎｄｔｈｅｉｒｓｏｌｉｄｓｏｌｕｔｉｏｎｓａｒｅｉｍｐｏｒｔａｎｔｍａｔｅｒｉａｌｓｆｏｒｐｈｏｔｏ ｅｌｅｃｔｒｏｎｉｃａｎｄｈｉｇｈｓｐｅｅｄｅｌｅｃｔｒｏｎｉｃａｐｐｌｉｃａｔｉｏｎｓ .Ｔｈｅｆａｂｒｉｃａｔｉｏｎｏｆｔｈｅｓｅｃｏｍｐｏｎｅｎｔｓｉｎｖｏｌｖｅｓｍａｎｙｃｏｍ ｐｌｅｘ ｐｒｏｃｅｓｓｅｓ.Ｆｏｒｅｘａｍｐｌｅ ,ｔｈｅｓｏｌｉｄａｎｄｌｉｑｕｉｄｐｈａｓｅｓｃｏｅｘｉｓｔａｔｎｅ…     

THE DETERMINATION OF THE RESIDUAL STRESS DURING THE FATIGUE CRACK EXTENDSION

１．ＩｎｔｒｏｄｕｃｔｉｏｎＦｏｒｅｓｔｉｍａｔｉｎｇｔｈｅｌｉｆｅｓｐａｎｏｆｔｈｅｗｅｌｄｉｎｇｗｏｒｋｐｉｅｃｅａｔｔｈｅｆａｔｉｇｕｅｌｏａｄ,ｈｏｗｄｏｅｓｔｈｅｌａｔｅｒａｌｒｅｓｉｄｕａｌｓｔｒｅｓｓｔｈａｔｉｓｖｅｒｔｉｃａｌｔｏｔｈｅｄｉｒｅｃｔｉｏｎｏｆｔｈｅｃｒａｃｋｅｘｔｅｎｓｉｏｎｃｈａｎｇｅｉｓｏｎｅｏｆｔｈｅｉｍｐｏｒｔａｎｃｅｆａｃｔｏｒｓａｆｆｅｃｔｉｎｇｔｈｅｅｘｔｅｎｓｉｏｎｏｆｔｈｅｆａｔｉｇｕｅｃｒａｃｋａｔｔｈｅｐｏｉｎｔｏｆｔｈｅｃｒａｃｋ．Ｔｈａｔ…     

Characterization of thermal sprayed hydroxyapatite powders and coatings

Calcium phosphate materials such as hydroxyapatite (HA) have biocompatible properties that can promote osteogenesis or new bone formation. Thermal spraying is an economical and effective process for coating the hydroxyapatite onto metal. It has been reported that plasma spraying changes the degree of crystallinity as well as the phase composition of the HA. This article reports the preparation and characterization of HA powders and coatings by two thermal spray processes (plasma and combustion flame) and suggests that the state of the starting powder adversely affects the coating characteristics. The raw HA powders are synthesized through a chemical reaction involving calcium hydroxide and orthophosphoric acid. Phase analysis using an X- ray diffractometer revealed that the synthesized powder consists of predominantly the HA phase. Calcined and crushed HA powders of various size ranges were fed into the plasma jet to produce HA coatings on metallic substrates. In addition, some HA powders were sprayed into distilled water by plasma spraying and combustion flame spraying to study powder melting characteristics. Other samples were plasma sprayed onto a solid rotating target to study atomization and impact behavior. The morphology of the rapidly solidified powders and thermal sprayed coatings were examined by scanning electron microscopy (SEM). An X- ray sedimentation particle size analyzer, laser diffraction particle size analyzer, and image analyzer performed the particle size analysis. Preliminary results indicate that particle cohesion, size range, and thermal treatment in the plasma affect the phase and structure of the as- sprayed coating, and some post- spray treatment may be necessary to produce a dense and adherent coating with the desired biocompatible properties.     

等离子喷涂人工骨涂层材料

等离子喷涂是一种常用的生物医用材料表面改性技术,被广泛应用于钛等金属人工骨的表面改性.为了满足人工骨涂层的临床应用需要,近年来发展了一些新的涂层材料和后处理工艺技术.利用火焰蒸汽处理技术对等离子喷涂羟基磷灰石涂层进行后处理,提高了涂层的结晶度,降低其在体液中的降解.经碱处理的等离子喷涂钛涂层,生物活性有了明显的改善.等离子喷涂硅灰石和硅酸二钙陶瓷是一类不同于传统磷酸钙系的新型生物活性材料,其性能和结构已被初步研究.同时介绍了等离子喷涂人工骨涂层材料在这几个方面的近期研究进展.     

Microstructural Development and Deposition Behavior of Titanium Powder Particles in Warm Spraying Process: From Single Splat to Coating

Warm spraying has been developed by NIMS, in which powder particles are accelerated and simultaneously heated, and deposited onto a suitable substrate in thermally softened solid state. In this study, commercially available titanium powder was sprayed onto steel substrate by the spraying process. Microstructural developments and deposition behaviors from a deposited single particle to a thick coating layer were observed by high resolution electron microscopes. A single titanium particle sprayed onto the substrate was severely deformed and grain-refined mainly along the interfacial boundary of particle/substrate by the impact of the sprayed particle. A successive impact by another particle further deformed the previously deposited particle and induced additional grain refinement of the remaining part. In a thick coating layer, the severe deformation and grain refinement were also observed. The results have demonstrated the complex deposition behavior of sprayed particles in the warm spraying using thermally softened metallic powder particles.     

Corrosion behavior of HVOF coated sheets

High velocity oxygen-fuel (HVOF) thermal spray coating finds application in industry due to its superior resistance to corrosion and thermal loading. In the HVOF process, the metallic powders at elevated temperature are sprayed at supersonic speed onto a substrate material. The powder granules sprayed impact onto each other, forming a mechanical bonding across the coating layer. In most of the cases, the distances among the particles (powder granules sprayed) are not the same, which in turn results in inhomogeneous structure across the coating layer. Moreover, the rate of oxidation of the powder granules during the spraying process varies. Consequently, the electrochemical response of the coating layer surfaces next to the base material and free to atmosphere differs. In the current study, the electrochemical response of a coating sheet formed during HVOF thermal spraying was investigated. NiCrMoNb alloy (similar to Inconel 625) wass used for the powder granules. Thermal spraying was carried out onto a smooth surface of stainless steel workpiece (without grid blasting), and later the coating layer was removed from the surface to obtain the coating sheet for the electrochemical tests. It was found that the corrosion rate of the smooth surface (surface next to the stainless steel surface before its removal) is considerably larger than that corresponding to the rough surface (free surface) of the coating sheet, and no specific patterns were observed for the pit sites.     

冷喷涂中粉末处理及复合技术研究进展

冷喷涂是近年来发展起来的一种固态材料沉积技术,具有沉积温度低、沉积速度大、沉积效率高等特点,在金属材料尤其是温度敏感的金属材料固态喷涂成型方面具有明显优势。冷喷涂中,喷涂粉末的状态(包括形状、尺寸和含氧量等)对整个涂层的影响较大,对冷喷涂粉末进行改性和合理设计显得十分重要。阅读和整理近年来冷喷涂研究领域中喷涂粉末的前处理技术,主要包括粉末预热和热处理以及粉末复合技术,粉末复合技术的主要方法有机械混合法、球磨法、造粒法和包覆法等。总结整理了各种技术的优缺点,可为冷喷涂过程中粉末处理技术的选择提供参考。     

超音速等离子喷涂WC-17Co涂层的工艺及性能分析

以低成本压缩空气和丙烷作为工作气体,采用超音速等离子喷涂制备了WC-17Co涂层,研究了喷涂功率对涂层组织、孔隙率和相组成的影响,测试了涂层的抗压性和耐磨性.结果表明,喷涂功率显著影响粉末的熔化和脱碳程度,功率过小时,WC颗粒熔化程度低;功率过大时,WC严重脱碳生成W₂C甚至W相.喷涂功率为65 kW制备的涂层孔隙率最低（0.87%）,未出现严重脱碳产物钨,涂层具有很强的抗压入变形能力,由于高硬度WC颗粒的存在,涂层的耐磨性显著提高,其磨损量仅为基体的15%,磨损形式由基体的严重磨粒磨损+粘着磨损变为涂层的轻微磨粒磨损.     

A new application field of plasma spraying technique to environmental depollution

To expand the application of plasma spraying technique, TiO2 coatings were prepared using agglomerated anatase TiO2 powder to solve the environmental problems. The composition and photocatalytic activity of plasma sprayed TiO2 coatings were investigated systematically. The content of anatase TiO2 in the sprayed coatings was approximate to 7%- 15%, which was influenced by the melting state of TiO2 powder in plasma spraying process. The surface of sprayed coating was very rough and the arithmetical mean deviation of the surface profiles (Ra) was in the range of 5.7 - 8.8 μm. Under lower arc current, the surface of the coating became rougher. The anatase to rutile phase transformation temperature of agglomerated anatase TiO2 powder was approximate to 1 173 K. The TiO2 coating sprayed under the arc current of 400 A had good photocatalytic activity for the relative high content of anatase phase in it. It is concluded that the application of plasma spraying technique to environmental field has been developed.     

Influence of Plasma Spray Parameters on the Microstructure and Property of ZrO2-7 wt%Y2O3 Coating

The plasma sprayed ZrO2-7 wt%Y2O3(7YSZ)coating has been widely applied in aircraft engine as a thermal barrier coating.In this study,the duplex TBC system(MCrAlY+7YSZ)were deposited onto 304 stainless steel substrate by APS.Four principal spraying parameters during the deposition of 7YSZ coating were optimized by using orthogonal experimental design,including the stand-off distance,plasma power,preheating temperature and powder feeding rate.Their influences on the coating’s microstructure,adhesion and its mechanical properties were studied and the optimized parameters were finally obtained.The results showed that the dependence of the spraying parameters on the properties of 7YSZ coating is highly correlated to the melting condition of the in-flight particles.     

Synthesis and Preliminary Tests of Suspension Plasma Spraying of Fine Hydroxyapatite Powder

The synthetic hydroxyapatite (HA, Ca₁₀(PO₄)₆(OH)₂) is a very useful biomaterial for numerous applications in medicine, such as e.g., fine powder for suspension plasma spraying. The powder was synthesized using aqueous solution of ammonium phosphate (H₂(PO₄)NH₄) and calcium nitrate (Ca(NO₃) · 4H₂O) in the carefully controlled experiments. The synthesized fine powder was characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM). The powder was formulated into water and alcohol based suspension and used to carry out the initial tests of plasma spraying onto titanium substrate. The phase analysis of sprayed coating was made with the XRD.     

Characterization of mechanical properties of suspension plasma sprayed TiO2 coatings using scratch test

The study aimed at characterizing mechanical properties of TiO₂ coatings obtained by the use of aqueous suspensions of fine rutile and anatase particles onto metal substrates. Thickness of the coatings was found with the use of optical microscope observations of metallographical cross-sections. The coatings morphology was found with scanning electron microscope (SEM) and their phase composition was determined by X-ray diffraction method. The mechanical properties were characterized using scratch test. The test enabled to characterize the adhesion of coatings by determination of critical force necessary to peel off the coatings from the substrate and, on the other hand, to estimate their cohesion by the measurement of the scratch hardness. The hardness was calculated using the width of the scratch and the value of force applied. The design of experiments (DOE) of spraying with the use of a 2³ full factorial plan was applied to rutile powder. The coatings were sprayed onto aluminium substrate. The DOE enabled to find the effects of three principal parameters, i.e. electric power input to plasma, spray distance and suspension feed rate onto coating adhesion expressed by critical force. A preliminary data for anatase powder sprayed with one set of operational parameters onto stainless steel substrate are also shown.