Electrodeposited diamond wheels for finish grinding require fine-grain diamonds. Promoting a reexamination of electrodeposition conditions. Initially, a previously proposed method involving distribution of diamond grit onto the wheel surface in an electrodeposition fluid was considered. This method uses two concentric cylinders and a J-type nozzle, both made of glass, with the inner cylinder containing a suspension of diamond grit in the electrodeposition fluid, and the outer cylinder containing electrodeposition liquid only. Improvements were made in the shape and dimensions on the inner cylinder, and the angle of tilt of the nozzle was changed from 60° to 70°. Electrodeposited diamond wheels were manufactured using the improved method, and grinding performance was then examined from the point of view of wheel wear and finished surface roughness. It is concluded that a current density 1A/m2yields finish grinding wheel having good performance.
The effects of the addition of water glass on specific surface areas and on the catalytic performance of self-cleaning porcelain enamel containing MnO2 were investigated by means of TG-DTA, adsorption isotherms and determination of weight loss of lard. The specific surface areas and catalytic performance of heat-treated MnO2 were markedly decreased by the decomposition of MnO2 to Mn2O3 at 550deg C. Addition of water-glass to glass frit lowered the glass transition temperature, prevented the decomposition of MnO2 to Mn2O3, raised the surface hardness of the enamel and lowered the firing temperature of the enamel by more than 100deg C compared to enamel without water glass.
The decomposition behavior of gelatine in the electrolyte and the effect of the decomposed species on Cu deposition have been investigated. The coeffect of gelatine and Cl- ion on Cu deposition was also studied. The results obtained are as follows. 1. The morphology of the Cu deposits changed with the molecular weight and concentration of the gelatine. Gelatine decomposition behavior also changed with the molecular weight. 2. The addition of gelatine increased the overpotential of the Cu deposition, while the addition of Cl- with the gelatine decreased the overpotential. 3. It was found from the impedance analysis using an equivalent circuit that a two-step copper deposition reaction, Cu2+→Cu+→Cu, proceeds with a hydrogen evolution reaction.
It was estimated that the ultrasonic effects were cavitation effects (jet flow, water hammer pressure by the jet flow and shock wave pressure), and it was demonstrated which of these effects was the most pronounced in the case of copper electrodeposited from cupric-EDTA solution. Generally, the radius at which bubbles collapse is about 1/30 of the initial radius, so jet flow rate was estimated at 120ms-1 and water hammer pressure at 200MPa. However, since bubble collapse was random, many jet flows were offset. The authors estimated the speed of most jet flows at 1∼2ms-1. Shock weve pressure was estimated at 1GPa or more, but since the actual electrode surface and received shock wave pressure locally, or simultaneously at random locations, the authors estimated that shock wave pressure was 1∼2MPa. The effects of ultrasound intensity, frequency, flow and hydrostatic pressure on current density, texture coefficient, hardness, particle size and surface morphology were also examined, and hints on the use of ultrasound in electrodeposition applications were obtained. Current efficiency was influenced mainly by the jet flow effect. The orientation and particle size of the crystals and hardness of film were influenced mainly by the water hammer pressure and shock wave pressure effects. The film became smoother as particles were collected in concavities by jet flows, and particles were compressed by water hammer and shock wave pressures. It was confirmed that the greater fineness of the crystals was due to shock wave pressure. The decrease in pin-holes was due to crystals being crushed or pushed into the pin-hole by water hammer pressure or shock wave pressure.
The decomposition mechanism of gold sulfite plating baths was investigated and stabilizing agents were evaluated with a view to improving bath stability. It was confirmed that Au metal and Au3+ ion were produced at bath decomposition, which proceeded based on a 3Au+→2Au+Au3+ disproportionation reaction. This shows bath stability will be improved by inhibiting the disproportionation reaction and the most effective agents that were inhibiting the dispropotionation of Au+ and thus improving bath stability were 2, 2'-dipyridyl and its derivatives including 0-phenanthroline and neocuproin. The Vickers hardness of the deposit from baths containing 2, 2'-dipyridyl was 66Hv, and the stress was lower than for the standard bath. Brightness was improved by the addition of As3+, but hardness and stress were increased.