National Research Council of Canada

Noranda Inc.

Henri L Levert

Serge Dallaire

Edouard Gervais

A method of on site application of an erosion resistant coating. When deposited on the surface of a metallic substrate, the coating comprises hard ferroboride phases bound with a ductile metallic phase. The ductile metallic phase is selected from metals which have a low affinity for oxygen. The preparation and composition of a cored wire adapted for use in application of the erosion resistant coatings are also disclosed.

Method of producing improved erosion resistant coatings and the coatings

Abrasion-wear resistant thermal sprayed stainless steel based coatings are disclosed, particularly arc sprayed stainless steel coatings containing titanium diboride crystals which impart hardness to the soft stainless steel matrix and enhance their resistance to hard abrasive media. There is also disclosed a process for making core wires composed of stainless steel sheaths and cores composed of a mixture of titanium diboride, stainless steel and certain additives. During the thermal spraying operation, the stainless steel sheath and the core material melt to form a composite coating containing fine hard titanium boride crystals dispersed within stainless steel. The arc sprayed stainless steel based coatings are more resistant to abrasion wear than solid pieces of type 304 stainless steel and other arc-sprayed stainless steel-based coatings available on the market. Although reference is made mainly to the arc spraying process, the core wires are suitable for other thermal spraying processes that use wires as the feed material, for instance combustion and arc-plasma spraying and weld overlay surfacing techniques.

Thermally sprayed titanium diboride composite coatings

A process for minimizing foam formation on the top surface of molten metal during free falling of molten metal, such as molten zinc, into moulds, launders or other containers is disclosed. The process comprises the steps of forming a body of substantially dross-free molten metal, introducing a non-oxidizing gas into the container to form an essentially non-oxidizing atmosphere with respect to the molten metal, free falling the molten metal from the body of molten metal into the container, and maintaining the molten metal during the free falling thereof under an essentially non-oxidizing atmosphere, so as to prevent entrainment of sufficient oxygen into the molten metal by the falling stream to form excessive quantities of bubbles having a tenacious oxidized film and which do not collapse when they float to the surface of the molten metal but rather produce undesirable foam on the surface of molten metal.

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CA

Henri L Levert