Abstract: A chemical vapor deposition method is provided for case hardening a ferrous metal interior tubular surface by exposure to diffusible boron with or without other diffusible elements such as silicon to enhance the wear, abrasion and corrosion resistance of the surface. The pack composition used allows for borosiliconizing of the interior surface without sintering or adhering to itself and/or adhering to the surface. The pack composition comprises between about 5% and about 20% by weight of a suitable source of boron; between about 2% and about 10% by weight of silicon material; between about 2% and about 15% by weight of an activator; and the balance being a non-sintering, non-adhering filler.

Abstract: A pack composition is disclosed for case hardening a ferrous metal to initially diffuse boron into the surface thereof and subsequently diffuse boron and silicon into the surface thereof. The pack composition comprises an amorphous boron, a silicon material, an alkyli earth, and a carbon bearing compound with the last named compound including a barium carbonate, a calcium carbonate and a hardwood charcoal and coke mixture.

Abstract: A pack composition is disclosed for case hardening a ferrous metal to initially diffuse carbon into the surface thereof and subsequently diffuse boron into the surface. The pack composition comprises a boron material and a carburizing compound with the last named compound including a barium carbonate, a calcium carbonate and a hardwood charcoal and coke mixture.

Abstract: A process is disclosed for case hardening of ferrous metal. In the process of the invention, the surface of the ferrous metal is exposed to diffusible carbon and boron in a furnace during multiple stages of a single thermal cycle without intermediate cooling. The furnace is maintained at a first temperature which enhances diffusion of the carbon to create a carburized substrate to a desired depth. The furnace temperature is then elevated to a second temperature to enhance diffusion of the boron to form an outer surface layer enriched therewith. This results in a gradual transition between the carburized substrate and the boronized layer.

Abstract: A process is disclosed for case hardening a ferrous metal. In the invention, the surface of the ferrous metal is exposed to diffusible carbon, boron and silicon in a furnace during multiple stages of a single thermal cycle. The furnace is maintained at a first temperature which enhances diffusion of the carbon to create a carburized substrate to a desired depth. The furnace temperature is then elevated to a second temperature to enhance diffusion of the boron and silicon to form an outer surface layer enriched with these elements. This results in a gradual transition between the carburized substrate and the boronized and siliconized layer.