The tuyere combustion zone has been studied on an experimental furnace by measuring dimensions and temperature in the raceway. The effects of variables such as the blast velocity, tuyere diameter, and coke size are studied. Expressions are derived for estimating the length, width, and height of the raceway in terms of the velocity and density of the blast air, tuyere diameter, and coke properties such as the size, density, and shape factor. Discussion is carried out according to the idea that the compressive force of blast to the coke bed is balanced with tendency of collapse of the raceway wall, and that coke in the raceway is fluidized by raceway gas. Measurements of operating blast furnaces by rod test are shown to be generally in good agreement with those on the experimental furnace.

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Pb-free solderable surface finishing is essential to implement Pb-free solder assembly in order to meet with the growing demand of environmental consciousness to eliminate Pb from electronic products. Two types of widely applicable Pbfree surface finishing technologies are developed. One is the multilayer-system including Pd with Ni undercoat. Heat-resistance of Pd enables whole-surfaceplating on to leadframe before IC-assembling process. The other is the doublelayer-system with low-melting-point-materials, for example, thicker Sn underlayer and thinner Sn-Bi alloy overlayer, dilutes Sn-Bi alloy's defects of harmful reactivity along with substrate metal and mechanical brittleness with keeping its advantages of solder-wettability and no whisker.

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