To clarify the sintering phenomena of Cu-Sn compact, characteristics of thermal dilation and electric resistance during sintering (in argon atmosphere up to 850°C) were studied. The results obtained were as follows.
1) Thermal dilation curves show that they have a maximum point at about 550-600°C and have three marked points at about 200, 400 and 700-800°C where expansion or shrinkage stop for a while, and that the largest shrinkage occurs overs 800°C. It is concluded that these temperatures correspond to those of liquid phase formation and phase transformation which are respectively due to the melting of Sn at 232°C, 6 formation (η→ε+L) at 415°C, liquid phase formation(γ→γ+L) at 710°C, and β formation (γ/+L→β+L) at 755°C.
2) Elctric resistance curves show that they have two marked peaks at about 200 and 700-800°C. It is considered that the peak at 200°C is owing to the increase of the contact point of grain caused by melting of Sn, and the other at 700-800°C is owing to that caused by liquid phase formation described above. Then, it is concluded that the structure of the Cu-Sn compact sintered over 800°C is completely mono-phase, α.

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The optical and electron micrographic examination of sintered Ni ferrite under the norme grain growth showed that pore remains at grain intersections when the cylindrical pore close and that subsequent grain growth changes the shape and distribution of the pore. That is boundary migration due to grain growth leads the pores to set on grain boundaries and som of them to isolate from grain boundaries.
Size, shape and population of the pores observed at these stages of sintering are subjected to statistical analysis, and a model for explaining the change of pores is proposed.

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The isothermal shrinkage of the compacts of stannic oxide powders containing 0, 1, 3 and 5 mol % of bismuth was measured by means of a shrinkage meter between 1150° and 1250 °C in air.
The shrinkage rate of stannic oxide powder was very small and its activation energy was calculated as 38 Kcal/mol.
By the addition of bismuth, the shrinkage was found to be increased. By the addition of 1-3 mol % of bismuth, no change in the lattice constant was observed from the X-ray analysis. Therefore it may be considered that bismuth ion is soluble in SnO₂ up to 3 mol % and is substituted for Sn ⁺in SnO₂. Assuming that bismuth in SnO₂ is trivalent state this substitution will increase the concentration of oxygen vacancy. Hence the diffusion of ions is promoted, as a result, the shrinkage rate of compact is accelerated.
The compound Bi₂(SnO₃) ₃ was detected in the compact containing 5 mol % of bismuth by X-ray analysis. The presence of Bi₂(SnO₃) ₃ decreases the shrinkage rate during sintering.

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Experimental studies were made on the flash resistance sintering of iron powder. The influences of electric charging and processing conditions on the mechanical properties of sintered compacts were studied. The results obtained are as follows.
(1) In order to obtain high density products, pressure more than 1 ton/cm² and correct sintering time are necessary.
(2) The density and tensile strength of the sintered compacts from electrolytic iron powder are higher than those of compacts from Hoganas iron powder.
(3) The finer the particle size of the iron powder used, the denser the structure of the sintered compacts obtained. Among the compacts blended in various weight ratios of coarse to fine iron powders, the compact blended with same weight of powders showed the highest sintered density.
(4) To get the sintered products with high density and uniform structure, acute angle and high projection on the sample are prohibited.
(5) Application of thin refractory metal plates between the electrode and the metal powder is effective to obtain high density sintered products.
(6) On the apparent density and tensile strength of the sintered compacts, the influence of the input power is greater than that of sintering atmosphere.

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