(under subclass 1) Processes involving arranging one or more distinct powder material layers or portions in contact with one or more distinct layers or portions of powder or solid material and uniting the layers or portions by sintering, or processes under subclass 1 which produces an article which includes an internal hollow space or processes under subclass 1 which involve making a porous article and infiltrating (i.e., impregnating) it.
(1) Note. Layers or portions of powder material are considered distinct if they differ with regard to chemical composition, particle size or degree of physical compaction, if they constitute individual preformed layers.
(2) Note. Processes herein included are those involving two or more distinct layers as in (1) Note above, in which one or more powder layers are united with one or more solid layers by a sintering step.
(3) Note. Processes for impregnating a sintered article by immersion or diffusion are excluded herefrom and are provided for in subclass 27.
SEE OR SEARCH THIS CLASS, SUBCLASS:
47, for processes in which during the sintering operation one layer melts and becomes dispersed throughout the other layer.
SEE OR SEARCH CLASS
216, Etching a Substrate: Processes, for the use of etching in removing one substance from another or for removing a portion of a substance (work) not otherwise provided for.
