Abstract: A sintered porous metal filter permitting passage of gases therethrough comprises a filter portion having specified pores for trapping dust as separated from the gas to be treated, and a support portion for supporting the filter portion, the support portion having pores greater than the pores of the filter portion to diminish the pressure loss of the gas to be treated, the filter portion comprising metal particles of small diameter, the support portion comprising metal particles having a greater diameter than the filter portion forming metal particles, the filter portion and the support portion being formed to provide an outer side and an inner side integral therewith by sintering the two kinds of metal particles by hot isostatic pressing. A catalyst reaction portion for rendering noxious components of the gas to be treated harmless is formed in the filter portion or the support portion, or as an independent catalyst layer.

Abstract: A sintered porous metal filter permitting passage of gases therethrough includes a filter portion having specified pores for trapping and separatin dust from the gas to be treated, and a support portion for supporting the filter portion. The support portion has pores greater than the pores of the filter portion to diminish the pressure loss of the gas to be treated. The filter portion includes metal particles of small diameter, and the support portion includes metal particles having a greater diameter than the filter portion forming metal particles. The filter portion and the support portion are formed by sintering the two kinds of metal particles by hot isostatic pressing to provide an outer side and an inner side integrally. A catalyst reaction portion is formed in the filter portion or the support portion, or as an independent catalyst layer to make noxious components of the gas harmless.

Abstract: The porous metal body of the inventtion has a porosity of 7 to 50%, pore sizes of 1 to 500 .mu.m and a pore distribution satisfying the relationship of:(D.sub.95 -D.sub.5)/D.sub.50 .ltoreq.2.5wherein D.sub.5 is the pore size on the cumulative distribution curve of the pore sizes at a cumulative frequency of 5%, D.sub.50 is the pore size on the curve at a cumulative frequency of 50% and D.sub.95 is the pore size on the curve at a cumulative frequency of 95%. The porous body is improved in porosity characteristics and mechanical strength.The porous metal body is prepared by pressing a metal powder to shape and sintering the shaped body by hot isostatic pressing, or alternatively by enclosing a metal powder in a capsule, subjecting the encapsulated powder to a primary sintering treatment in an isostatic medium to form a primary sintered porous body and heat-treating the sintered body with the capsule removed or without removing the capsule.