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Influence of titanium powder characteristics and heating rate on the liquid phase sintering of Fe8%Ti powder compacts.

Ciaś A., Stoytchev M.

Inżynieria Materiałowa

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1998

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R. XIX, nr 4

1131-1136

EN

In view of interest in the use of titanium as an alloying element to the sintering of iron-based powder compacts, an examination has been made of the influence of the characteristics of the titanium powder and heating rate on sintering process. Transient liquid phase sintering was examined for Fe8%Ti powder mixtures. The effect of additions of narrow sized fractions of titanium powder and heating rate on the dimensional changes obtained on sintering Fe8%Ti compacts made with Hoganas NC 100.24 sponge iron and 7, 16, 56 and 200 micrometres titanium powders has been determined. The experimental plan included the effects of several processing variable, such as titanium paricle size, heating rate, sintering temperature and sintering time.Two types of experiments were used to study sintering. The effects has been examined in relation to the sintering mechanism by dilatometry, using a comuterised precision vacuum dilatometer Netzsch 402S with an extended range, constant load single pushrod. In addition to dilatometer experiments, batch sintering was conducted in a vacuum furnace. It was found that the use of fine titanium powder and controlled heating rate reduced the dimensional change.

2

Influence of the production parameters on the properties of the sinters made from displaced copper powders.

Leżański J., Gacek S., Radoń A., Olszewska I.

Inżynieria Materiałowa

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1998

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R. XIX, nr 4

1203-1205

EN

In this paper the production parameters influence on the properties of sinters made from copper powder which are obtained on the first stage of hydrometallurgical processing by displacing from copper fire scale, are presented. Pressed powder compacts density and sinters density were investigated. Also sinters bending strength, hardness, electric resistance were measured and sinters structure was observed and analysed. In described experiment sinters with very high properties were obtained and this indicate high suitability of the use of hydrometallurgical copper powders for application in powder metallurgy technology.

3

Effect of heating rate on the synthesis of nickel aluminides by reactive sintering.

Gialanella S., Pieczonka T., Molinari A., Kazior J.

Inżynieria Materiałowa

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1998

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R. XIX, nr 4

909-912

EN

Dimensional changes occuring during reactive sintering of three different elemental nickel - aluminium powder mixtures were investigated. Sintering process of powder compacts was curried out under vacuum in a horizontal dilatometer at a various heating rates. The synthesis reaction proceeded with a sudden release of heat and sudden dimensional changes, corresponding to the appearance of liquid phase in the system. Heating rate is a crucial parameter affecting the dominant sintering mechanisms: both extensive shrinkage as well as extensive swelling were observed for each investigated mixture composition depending on the actual heating rate. At slower heating rate the synthesis reactions were initiated and developed between solid powders of nickel and aluminium. In these cases, owing to the limited amount of liquid phase which developed, a swelling of compacts was observed. However, at the higher heating rate solid state reactions were limited and after transient swelling also shrinkage was observed.