.~ Having composition, density, or hardness gradient
DEFINITION
Classification: 428/610
(under subclass 544) Subject matter wherein the composition of the stock-material* varies gradually from being one composition to being another composition, without the formation of distinct layers, or wherein such variation takes place within a single layer of the material, or wherein such a variation occurs in the density of the material or layer.
(1) Note. The gradual nature of the composition variation must be explicit for the patent to be classified herein.
(2) Note. In regard to a "diffusion" layer in a metallic composite, see the definition to subclass 615, (6) Note.
SEE OR SEARCH THIS CLASS, SUBCLASS:
170, for a nonmetallic* sheet, web or component which varies in thickness and density.
217, and 218, for a nonmetallic* stock-material* product having distinct layers of differing hardness or density. 547, for particulate metal stock having a composition, or density gradient.
941, for a collection of patents which concern metallic stock produced by a method which includes solid state diffusion of metals to the disappearance of an original layer.
SEE OR SEARCH CLASS
51, Abrasive Tool Making Process, Material, or Composition, for an abrasive tool making composition comprised of metal or metal oxide.
148, Metal Treatment, appropriate subclasses for processes of treating metal to modify or maintain the internal physical structure (i.e., microstructure) or chemical properties of metal and which may result in a gradual variation in composition with or without formation of distinct layers but identified in terms of the separate compositions. See Class 148,
206+, for processes of carburizing or nitriding metal; subclasses 240+ for reactively coating of metal; or subclasses 516 for processes of treating layered metal stock or article. If metal casting, fusion bonding, machining, or working is involved, there is a requirement of significant heat treatment as described in section III, A, of the Class 148 definition.
