Patent GB-491659-A (GB)
Title: Improvements in or relating to bonded abrasive articles
IPC: C09K3/14
Filed: 1937-03-06
Abstract: A dense non-porous abrasive article comprises preformed aggregates of diamond or hard carbide abrasive such as boron carbide and a metallic bonding material, bonded by another bonding material which is relatively soft and yielding and which substantially fills all spaces between the aggregates.  The abrasive particles may be in the form of dust.  Metallic bonding materials specified are copper, nickel, cobalt, iron and silver; these metals preferably have alloyed therewith materials which will render them hard and brittle, e.g. copper can be embrittled by the addition of tungsten, aluminium or tin.  The abrasive particles may be incorporated in the metallic bonding material by mixing the particles with the powdered metal, compressing, and heating to about or above the melting point of the metal; the heating should be effected in a non-oxidizing atmosphere such as may be produced by the deposition of finely divided carbon on the mix or by the use of an atmosphere of hydrogen, it is stated that an atmosphere of hydrogen facilitates the wetting of diamond particles by the metal.  The mixtures may be subjected to a jarring action during the heating.  The mixture is then cooled and broken up and bonded with the other bonding material.  Bonding materials specified for binding the aggregates are thermosetting resins such as phenolic condensation products, the resin may be in the form of a solution or of a mixture of the resin in liquid and solid form; thermoplastic resins such as vinyl acetate resins; mixtures of thermosetting and thermoplastic resins; and metals.ALSO:A dense non-porous abrasive article comprises preformed aggregates of diamond or hard carbide abrasive such as boron carbide and a metallic bonding material, bonded by another bonding material which is relatively soft and yielding and which substantially fills all spaces between the aggregates.  The abrasive particles may be in the form of dust. Metallic bonding materials specified are copper, nickel, cobalt, iron and silver; these metals preferably have alloyed therewith materials which will render them hard and brittle, e.g. copper can be embrittled by the addition of tungsten, aluminium or tin.  The abrasive particles may be incorporated in the metallic bonding material by mixing the particles with the powdered metal, compressing, and heating to about or above the melting point of the metal; the heating should be effected in a non-oxidizing atmosphere such as may be produced by the deposition of finely divided carbon on the mix or by the use of an atmosphere of hydrogen, it is stated that an atmosphere of hydrogen facilitates the wetting of diamond particles by the metal.  The mixtures may be subjected to a jarring action during the heating.  The mixture is then cooled and broken up and bonded with the other bonding material.  Bonding materials specified for binding the aggregates are thermosetting resins such as phenolic condensation products, the resin may be in the form of a solution or of a mixture of the resin in liquid and solid form; thermoplastic resins such as vinyl acetate resins; mixtures of thermosetting and thermoplastic resins; and metals.