Spray metallization

By far, the largest appHcation of zinc powder is for solution purification in electrolytic zinc plants. This appHcation consumed an estimated 17,700 t of powder in 1980. Zinc powder is also used in primary batteries, frictional materials, spray metallizing, mechanical plating, and chemical formulations. 

BS2569 Sprayed Metal Coatings. Part 1 Protection of Iron and Steel by Aluminum and Zinc Against Atmospheric Corrosion. ... 

Zinc or aluminum metal spray Sprayed metal coatings are porous and should be sealed after application by applying a sealer coat (i.e. a thin coat such as an etch primer) or a thinned version of the final coating system. Oil-based systems should not be used. Metal spray coatings can have excellent durability without overcoating with paint and, particularly for aggressive conditions it is preferable to leave them with sealer only. 

After suitable surface preparation, e.g. blast cleaning, low-alloy steels can be coated by paints, sprayed metal coatings, etc. and there is some evidence that such coatings last longer than on mild steel under similar conditions of exposure. ... 

The metal spraying operation using zinc or aluminium as a protective coating is usually followed by a painting scheme. The choice of sprayed metal and paint scheme depends on the service conditions , but normally this type of system is used on prestige buildings or structures, where longevity is of prime importance and maintenance requirements need to be kept to a minimum. 

Lead is a toxic metal and rigid precautions against lead poisoning are essential. Sprayed lead is, like other sprayed metals, porous, and the sprayed layers will not as a rule withstand attack by strong acids. On the other hand, lead from 0-13 to 0-25 mm (0-005 to 0-01 in) in thickness has proved extremely useful in atmospheres containing sulphuric acid. In this case the pores in the lead become blocked with lead sulphate, with the result that complete protection is assured. In the event of mechanical breakdown, lead does not exhibit any sacrificial action and therefore corrosion may lift the lead layer. 

The strength and adhesion of sprayed metal coatings are extremely difficult to measure with precision, and the properties of sprayed metals vary greatly with the spraying conditions and with the conditions of test. It is difficult, therefore, to correlate the values taken from the literature on the subject. For instance, American workers produce tensile test pieces by depositing on to 9-5 mm (0-375 in) steel tube and then machining out the tube. By this method the results shown in Table 12.7 were obtained. 

On the other hand, the ultimate strength obtained by testing solid sprayed bodies in the UK gives values about one-third of those in Table 12.7. The density of sprayed metal is between 10 and 15% lower than that of the wrought metal. 

Table 12.8 Hardness values (Brinell) for solid blocks of sprayed metal ...

Hardness values ascertained for solid blocks of sprayed metal are given in Table 12.8. Values obtained in America on deposits 0-76mm in thickness were about two-thirds of those given in this table. Figures for shrinkage of various deposits are given in Table 12.9. 

Adhesion is mechanical. For anti-corrosion protection by zinc or aluminium, an adhesion value of about 3MN/m is sufficient 7MN/m is typical and more than 15 MN/m can be obtained. There is no alloying to the substrate as the temperature of the sprayed metal is quite low when it reaches the steel surface (this can be demonstrated by spraying onto glass which does not crack with the limited heat received). 

Bailey, J. C. and Porter, F. C., Sprayed Metal Coatings for the Protection of Structural Steel-A Fresh Appraisal, Const. Steel, 12-19, Feb (1972) (Reprinted by American Welding Society)... 

Bailey, J. C. Corrosion Protection of Welded Steel Structures by Metal Spraying, Metal Constr. 15 No. 5, 264-270 (1983)... 

Plasma spraying Metals, or refractory materials or composites are applied by melting in an ionised inert gas M, tantalum, molybdenum, alumina, zirconia M2 a variety of metallic substrates... 

Carter, V. E. and Campbell, H. S., Protecting Strong Aluminium Alloys Against Stress Corror sion with Sprayed Metal , British Corrosion Journal, 4, No. 1, 15-20, Jan. (I%9) and 4 No. 4, 1%-198, July (1%9)... 

Protection by Sprayed Metal Coatings, The Welding Institute, London (1968)... 

Protection of Iron and Steel against Corrosion and Oxidation at Elevated Temperatures , Sprayed Metal Coatings, BS 2569 Part 2 (1965)... 

Ballard, W. E., Melal Spraying and. Sprayed Metal, Griffin, London (1948)... 

Mold construction FRP spray metal, cast aluminum gusket seal, air vents, self-sealing injection port FRP FRP, spray metal, cast aluminum, pinch (land) Metal, shear edge High grade steel shear edge... 

The combustion temperature of soot particulates can be lowered by the addition of an oxidation catalyst in the form of fuel additives[2], by spraying metal salt solution on an accumulated soot or by the impregnation of filter walls with an oxidation catalyst. For the last option, oxides of supported metals are considered to be... 

Store OPA in a cool, well-ventilated area away from heat, open flame. Avoid contact with water mists or sprays, metals, alkaline materials, and some organics. Reacts readily with DF or DC, producing extremely toxic compounds (GB or a chlorine compound similar to GB). 

Stability Does not spontaneously decomposes but is reactive. Avoid contact with water mists or sprays, metals, alkaline materials, and some organics. 

The spray metal" technique was invented in order to obtain good contact between extremely thin and short bridge wires and leads. Such bridges are used in newer type electric primers which are capable of being actuated by an extremely small energy input... 

Heavy Duty Industrial Spray Metal. Cleaner Concentrate F-544... 

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