The Structure,Texture and Growth of Bronze Electrodeposits on Polycrystalline Substrates

A study of the electrodeposition of Cn-Sn bronzes from a cyanide-stannate bath under potentiostatic conditions at 65°C has been made. It has been shown that the results are in agreement with those obtained previously under galvanostatic conditions. The growth and textures of the deposited alloys were also investigated. Continuation of the structures of cube-textured copper cathodes was most pronounced at intermediate overpotentials i e 500–650 mV. Under these conditions the initial base-oriented growth gave way to fibrous structures with increasing deposit thickness. At low overpotentials (300 mV) metallographic evidence indicated considerable lateral growth in the deposits and the texture was found to be [111] whereas at high overpotentials (700–800 mV) growth was mainly outward and the texture was [110]. These results are in agreement with theoretical predictions concerning ‘free-growth’ textures and suggest that little adsorption takes place under these conditions. At intermediate potentials the [100] texture was found, often with a mixture of [221] or [211] and it is suggested that these intermediate textures are associated with adsorption processes. When the [100] texture was found a second [100] axis of the deposit crystals was aligned in a specific direction and it is believed that this may be due to the presence of an alloying element rather than to the direction of current flow.     

Importance of the Texture Index for Nickel Electrodeposits

Investigations of the properties of electrodeposited Ni-Mn-S layers are reported. The correlation between the texture, the texture index, and three groups of interactions, incorporated impurities, structural characteristics and mechanical properties, is described. It can be seen that the microhardness and ductility as well as the crystallite size and microdeformation correspond clearly to the texture index, whereas the impurities have no big influence on the texture development.

These results show that the texture index of the electroplated layers is not only an X-ray diffraction parameter, but it can very well describe the macroscopic materials properties.     

Properties and Behaviour of Precious-Metal Electrodeposits for Electrical Contacts

The significance of hardness, thickness, resistivity and surface-cleanliness of precious-metal electro- deposits for electrical contacts is discussed and illustrated. Exploratory studies have been made to assess the protective value and mechanical wear of gold, palladium and rhodium plating deposited from conventional electrolytes. It is concluded that the porosity of the coating is a highly important factor in determining the behaviour of electrodeposits. Recommendations are made regarding suitable thickness of deposit for the respective metals.     

Studies on the Mechanism,Structure and Microhardness of Ni-W Alloy Electrodeposits

The electrodeposition of Ni-W alloy has been studied on the glassy carbon electrode by the cyclic voltammetry and potentiostatic step methods. It has been found that electrodeposition of Ni-W alloy involves an intermediate valence tungsten oxide which inhibits hydrogen evolution. Ni-W alloy electrodeposition occurs by a mechanism involving progressive nucleation followed by three dimensional growth.

The structures of nickel-tungsten alloy deposits were analyzed by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The XRD results from Ni-W alloy deposits reveal a face-centered cubic solid solution, the microstructure of the deposits exhibit (111) preferred orientation. The lattice constant and microhardness of Ni-W alloy deposit increase as the tungsten content increases, the XPS results of Ni-W alloy deposits indicate that the nickel and tungsten of the deposits exist in the metallic state, but the Ni-W alloy deposit with a tungsten content of 40.7% is an intermetallic compound. The XPS results of the deposit with tungsten content of 40.7% show that the atomic ratio of Ni to W is 4:1, so β-Ni₄ W alloy can be obtained by electrodeposition and its microhardness (Hv) is as high as 672.8.     

The Structure and Growth of Electrodeposits,and the Modifications Caused by Brightening Agents

Recent electron-diffraction evidence of the structure and conditions of growth of condensed deposits and of electrodeposits leads to the conclusion that during electrodeposition under the conditions usually used, the surface quickly reaches a temperature often as high as 600°C. or even more.

A detailed study of electrodeposits of silver from a cyanide bath on electropolished (110), (100) and (111) faces of a silver single crystal has shown that between the initial stage of parallel overgrowth and the random polycrystalline (and later one-degree orientated growth) there is, above a minimum critical c.d., an intermediate twinning of the single-crystal overgrowth, which accounts for the development of the random crystals. This critical c.d., for a given bath, is highest on the crystal faces having the highest number of atoms (or potential troughs) per unit area, and the more this c.d. is exceeded the more rapidly is twinning developed and in turn gives place to random crystals. This c.d. increases with increasing bath temperature. The effect of varying the bath composition was also explored.

For comparison, the effects caused by presence of a small proportion of addition agents (CS₂, thiosemicarbazide, thiourea, urea and KCNS) is also briefly described. Widely different effects on the crystal habit were caused by the various agents investigated. It is concluded that brightening results when the crystals, whether of microscopic size or not, form surfaces which are large and smooth relative to the light wavelength.     

Thermal Expansion,Electrical Resistivity,and Spreading Area of Sn-Zn-In Alloys

Thermal expansion and electrical resistivity of alloys based on Sn-Zn eutectic with 0.5, 1.0, 1.5, and 4.0 wt.% additions of In were studied. Thermal expansion measurements were performed using thermomechanical analysis tester over 223-373 K temperature range. Electrical resistivity measurements were performed with four-probe method over 298-423 K temperature range. The electrical resistivity of alloys increases linearly with temperature and concentration of In; also coefficient of thermal expansion of the studied alloys increases with In concentration. Scanning electron microscopy revealed simple eutectic microstructure with In dissolved in Sn-rich matrix. The results obtained were compared with the available literature data. Spreading tests on Cu of Sn-8.8Zn alloys with 0.5, 1.0, and 1.5 at.% of In were performed. Wetting tests were performed at 250 °C, by sessile drop method, by means of flux, and wetting times were 3, 8, 15, 30, and 60 min. In general, no clear effect of wetting time on spreading was observed.     

The Structure and Protective Properties of Zinc and Nickel Alternate Electrodeposits

A NEW TYPE of coatings consisting of a large numberof laminar deposits has been the keen subject of muchresearch,because these layered-structure coatingspossess improved properties or novel phenomenon suchas increased mechanical strength,micro-hardness,giantmagnetoresistance and corrosion resistance[1"6'.Thesecoating systems with individual layers making upoverall structure are also called compositionallymodulated multilayer(CMM)coatings'3"5'.In view ofthe plating historical use of surface…     

The Effect of Brush Plating on the Structure and Wear Properties of Electrodeposits

In this work, the structure and wear properties of brush plated electrodeposits were investigated. An additive free sulphamate solution was used for plating with different methods of solution supply as well as conventional bath plating, and the structures were investigated by TEM and X-ray diffraction.

The structure of the nickel sulphamate deposit obtained by brush plating with pumped solution supply was found to resemble that of bath plated deposits. When solution supply was realised by dipping of the anode, the coatings had a more fine grained structure and higher hardness.

Ball-on-ring tests were carried out on samples brush plated with different nickel and cobalt alloy coatings. A comparison was made with specimens bath plated with hard chromium. The cobalt and chromium deposits gave similar results, while nickel coatings were found to be less wear resistant.     

经验电子理论中与温度相关的价电子结构计算模型

通过合金平均线膨胀系数,建立起与温度相关的合金价电子结构计算模型,对该模型的理论基础进行了分析,研究了Cu和钢中γ-Fe-C含碳奥氏体晶胞价电子结构与温度的相关性。结果表明,温度可以显著影响合金价电子结构,温度升高时,其晶格常数增加,原子向较低杂阶迁移,各键的共价电子对数na及价电子结构中的相结构因子（nA、∑nc和FC^D）均出现了不同程度的下降。     

Hardness and the Poushing of Electrodeposits

Some of the published information that will help an engineer to select a painted metal-sprayed coating for a structure is reviewed, and results of recently-completed field trials on shop-coat paints for sprayed metals are reported. When designing a new steel structure, the engineer must decide on a suitable protective scheme bearing in mind how long the structure will be in use, the costs of protection and maintenance, the risks inherent in coating failure, the need for decoration and the practicability of the scheme chosen. The paper sets out to review his sources of information, to outline the relevant planning and design considerations, and to describe the principles on which the selection of the protective scheme should be based. B I S R A research on the subject is described. Further progress is expected from the exchange of practical experiences linked to field trials and laboratory studies, and the paper ends by quoting several practical examples of steel structures successfully protected by flame-sprayed metal coatings and paint.     

Investigation of Cold Rolling Texture and Recrystallization Texture in NiW Substrates

NiW alloys were fabricated by cold isostatic pressing, the W content being 5, 7 and 9.3 at%, respectively. The NiW substrates were obtained by rolling assisted biaxially texturing. The cold rolling and recrystallization textures of NiW substrates were systematically studied by X-ray and EBSD, which revealed a variation of rolling texture in NiW substrates with increasing W content, which also influenced the copper (C) type and brass (B) type texture, as well as the transition between them. In addition, the ...     

Effect of Alloying Elements on the Electrical Resistivity of Aluminum Alloys

The electrical resistivities of aluminum alloys containing Cu, Ge, Zn, Ag, Cd, and Mg were found to increase linearly with the atomic percentage of the solute atoms. Application of Linde’s rule to these data suggests that each aluminum atom contributes 2.5 electrons to the metallic bond.     

退火温度对Fe73.5Cu1Mo3Si14.5B8合金电阻的影响

研究了退火温度与晶化相结构的关系,讨论了退火温度对Ｆｅ７３．５Ｃｕ１Ｍｏ３Ｓｉ１４．５Ｂ８合金电阻的影响,结果表明,α－Ｆｅ粒子在４６０－５６０℃范围内几乎不长大,但温度高于５６０℃时,晶粒尺寸明显长大;随退火温度的升高,Ｆｅ７３．５Ｃｕ１Ｍｏ３Ｓｉ１４．５Ｂ８合金的电阻率呈下降趋势。     

电阻率对工程陶瓷电火花加工性能的影响研究

常用的工程陶瓷电阻率较高,直接采用电火花加工,性能较差。以ZnO/Al_2O_3陶瓷为例,研究了电阻率和脉冲宽度、脉冲间隔、工具极性等工艺参数对电火花加工工艺性能的影响。结果表明:采取合适的放电加工参数,在ZnO/Al2O3的电阻率达到3410Ω·cm时仍可对其进行有效的电火花加工。     

聚硅氧烷转化Si-O-C陶瓷的电阻率

由聚硅氧烷裂解制备出Si-O-C陶瓷，其电阻率为2220Ω·cm。在聚硅氧烷中添加Al和MoSi2可以制备出低电阻率的Al／Si-O-C和MoSi2／Si-O-C陶瓷。制备温度对材料电阻率有很大的影响。     

Effect of Initial Goss Texture Sharpness on Texture Evolution and Magnetic Properties of Ultra-thin Grain-oriented Electrical Steel

In this study, high-and low-grade grain-oriented electrical steels were used as the initial materials to produce0.08-mm-thick sheet with one-step cold-rolling method. Electron backscattering diffraction analysis technique and X-ray diffraction texture analysis technique were adopted to investigate the effect of initial Goss texture sharpness on texture evolution and magnetic properties of ultra-thin grain-oriented electrical steel. The results showed that primary recrystallization and secondary recrystallization were the main processes that occurred during annealing. The induced factors for secondary recrystallization of two grades samples were not consistent. The high-grade samples presented texture induction mechanism, while the low-grade samples revealed strong surface-energy induction mechanism. The initial Goss texture sharpness had a great impact on texture evolution and magnetic properties of ultra-thin grain-oriented electrical steel. The Goss texture component formed after primary recrystallization was stronger, and better magnetic properties were obtained at low frequencies. For low-grade samples, secondary recrystallization enhanced the intensity of Goss texture, and both grain size and texture contributed to better high-frequency magnetic properties after secondary recrystallization. By controlling the annealing process, the magnetic properties of low-grade products could be significantly improved, thus achieving conversion from low-grade to high-grade products.     

Texture Formation in Hot Rolling of Electrical Anisotropic Steel

Metal Science and Heat Treatment - Processes of structure and texture formation in hot rolling of electrical anisotropic steel are studied. It is shown that the structure of the surface layers of...     

A Preliminary Investigation of the Formation of Cracks in Hard Chromium Electrodeposits and the Evolution of Hydrogen During Deposition

Experiments are described in which the cathode in a chromium deposition cell is observed continuously at high magnification whilst deposition is taking place.

It is shown that the release of bubbles of hydrogen from the surface of the cathode is a discontinuous process occurring for well defined periods at regular intervals of time. Periodic cracking of the surface of the cathode has been observed and is found to be associated with the discontinuous evolution of hydrogen.     

温度对多元铜合金高温电阻率的影响

利用赛贝克电阻率测试仪测试了Cu-Bi-Al合金在不同温度下的电阻率.结果表明.在本实验温度范围内,Cu-Bi-Al合金的电阻率随着温度的升高而增大,当温度从25℃升至600℃时,电阻率由10.861×10-8Ω·m提高至18.208×10-8Ω·m.并对该合金电阻率的变化进行初步分析.