The purpose of this Defence Standard is to provide designers and users with advice on the application of flame sprayed coatings, principally for wearing surfaces. It includes cleaning, preparation of surfaces, design considerations, metals to be applied, quality control, inspection, and testing.
It is not intended to apply to aerospace parts and equipment.
This Defence Standard is divided into three parts:
Part 1, Unfused metal coatings
Part 2, Fused metal coatings
Part 3, Ceramic and cermet coatings.
Part 1, Unfused metal coatings, deals with the use of flame sprayed metal coatings to recover worn or mis-machined components with similar or dissimilar metals, to provide wear resistance, including hard facing, and to provide resistance to high and low temperaturs corrosion. The process also covers the application of metals to either metallic or various non-metallic surfaces for the purposes outlined above, and it embraces coatings for electrical purposes such as conductivity, screening, etc.
By way of example, the following are typical applications:
(1) Crankshafts and various types of rotating and reciprocating shafts sprayed for wear and/or corrosion resistance with such metals as carbon steel, stainless steel, chromium and other alloy steels, molybdenum, etc.
(2) Hydraulic rams, etc, sprayed for wear and/or corrosion resistance with such metals as carbon steel, stainless steel, bronzes, aluminium bronze, etc.
(3) Mating surfaces of components such as ball races, flywheels, etc, which are assembled using either shrink or interference fits, sprayed with carbon steel, stainless steel, molybdenum, etc.
(4) Roll faces for wear and/or corrosion resistance sprayed with carbon steel, stainless steel, bronzes, aluminium, etc.
(5) Exhaust pipes, silencers, hot gas ducts, chimneys, and burners sprayed with aluminium, to a thickness of approximately 0.18 mm, to provide high temperature corrosion resistance up to 500ºC.
(6) Exhaust manifolds, furnace chairs, and furnace mechanical handling parts sprayed with aluminium, to a thickness of approximately 0.18 mm, sealed and heat-treated to provide high temperature corrosion resistance up to 950ºC.
(7) Furnace boxes and covers sprayed with nickel-chromium with an aluminium overlayer, to a thickness of approfimately 0.38 mm, to provide high temperature corrosion resistance up to 1100ºC.
(8) For electrical conductivity, wood sprayed with copper for transformer stray current collector rings, plastics sprayed with copper for printed wiring boards, graphite sprayed with copper for furnace electrodes. Thickness of deposit varies according to application.
(9) For electrical screening, radio valves and the walls, floors, and ceilings of radio transmitter rooms and hospital operating theatres sprayed with copper. Thickness of deposit varies according to application.
This Standard must not be taken as approval to apply any flame sprayed coating to a component without the written consent of the purchaser or owner. This written consent may be in the form of a contract or order, or may be in the form of written permission from the Design/Approval Authority concerned.
If this Standard should be found unsuitable for a particular requirement the Director of Standardization shall be informed of the circumstances.