Tin coatings thickness

HVl the TiN-coating (thickness -3 pm) remained almost unchanged with no microscopic defects.These initial results, which of course must be optimized, highlight the significant potential of combined processes for CVD-coated forming tools. 

The amount of hydrogen accumulated within the lifetime of the container is determined not only by the tin coating thickness, the temperature, and the chemical nature of food in contact, but most often by the composition and structure of the base steel. The rate of hydrogen evolution is increased by cold working of the steel (see Section 8.1), which is standard procedure for strengthening the container walls. Subsequent low-temperature heat treatment, incidental or intentional, may increase or decrease the rate (see Fig. 8.1, Section 8.1). 

Tin is used in various industrial appHcations as cast and wrought forms obtained by rolling, drawing, extmsion, atomizing, and casting tinplate, ie, low carbon steel sheet or strip roUed to 0.15—0.25 mm thick and thinly coated with pure tin tin coatings and tin alloy coatings appHed to fabricated articles (as opposed to sheet or strip) of steel, cast iron, copper, copper-base alloys, and aluminum tin alloys and tin compounds. 

The coating thickness may range from 0.0025 to 0.05 mm, depending on the type of protection required. Pure tin coatings are used on food-processing equipment, milk cans, kitchen implements, electronic and electrical components, fasteners, steel and copper wire, pins, automotive bearings, and pistons. 

For articles that require only a very thin film of tin, seldom exceeding 0.8 p.m immersion tin coatings are appHed. The process is based on chemical displacement by immersion in a solution of tin salts. Recently, a new autocatalytic tin-deposition process was developed at the research level. It promises to be useful to coat any base material including plastics, in addition to providing coatings of any thickness desired (21). 

Fig. 4. Multilayer coatings on cemented carbide substrates, (a) 73% WC—19%(Ta,Ti,Nb)C—8%Co alloy with a TiC—TiCN—TiN coating of about 10 )J.m total thickness, (b) 85%WC—9%(Ti,Ta,Nb)C—6%Co with a TiC—AI2O2—TiN coating about 9 lm thick, (c) 86%WC—8%(Ta,Ti,Nb)C—6%Co with TiCN...

Fig. 12.9 Corrosion resistance of tin-nickel electrodeposit impaired by pseudomorphic porosity originating on cold-rolled steel surface (left). Panel on right has had the shattered grain surface removed by chemical polishing (0-125 iim removed). Coating thickness 15 iim-, panels exposed 6 months to marine atmospheric corrosion (Hayling Island)...

Hot dipped tin coatings, like galvanised coatings, have practical thickness limits and possess an under-layer of intermetallic compound, usually described as the alloy layer. 

A hot-dipped tin coating on steel has a layer of FeSnj at the interface between the tin and the steel. This alloy grows very slowly in comparison with the more complex alloy layers formed in galvanising and in aluminising. It usually comprises 10-20% of the total coating thickness. 

Alloy formation is faster on copper than on steel and tends to be more irregular. With coating thicknesses of 1 /im or less, the thickness of the alloy layer may amount to half that of the complete coating. It consists of a thin layer of CujSn adjacent to the copper and a thicker layer of Cu Snj adjacent to the tin. 

Hot-dipped tin coatings are difficult to apply outside the thickness range of 8-38 jtm and hot-dipped zinc coatings do not normally greatly exceed 50 m in thickness. Hollow sections and excessively large articles may be impractical to handle by the hot-dipping process and very thin sections may be subject to much distortion. 

Tin is applied by hot-dipping or electrodeposition and has a similar corrosion behaviour to that of zinc. Coating thicknesses are usually in the range 12-50 tm, and in the lower portion of this range coating porosity can be a factor to be taken into account (see discussions by Kochergin and Gonser and Strader ). 

Thickness of tin coatings The thicknesses of the various types of tin coating are shown in Table 13.11. 

As a general guide to the thickness of coating desirable for various applications, the requirements of BS 1872 1964 for electrodeposited tin coatings are shown in Tables 13.12 and 13.13. 

Table 13.12 Thickness suggested for electrodeposited tin coatings on ferrous components...

General thickness requirements for electroplated tin coatings on ferrous and non-ferrous substrates are contained in BS 1872 1984 and ISO 2093 and these are essentially the same as those in Tables 13.12 and 13.13. 

Tin plate, thickness of tin coating on, determination by x-ray spectrography, 148, 149, 157, 158 Tissues, determination of dry weight by absorptiometry, 297-300 Tissue sections, biological, determination of mineral elements in, 301-305 Titanium, as internal standard in vanadium determination, 188 determination by x-ray emission spectrography, 222, 329 trace analysis by x-ray emission spectrography, 163, 225-229 Topaz, as analyzing crystal, 116-118, 220, 318-327 Total reflection, 112, 117... 

Fig. 11. Dependence of the peel strength of tin plate/epoxy systems on coating thickness for coatings cast from DTPM and methyl cello-solve. These theoretical curves were constructed using experimental values for modulus, critical coating thickness, solvent evaporation rate, solution concentration and interfacial work of adhesion96 (Reprinted from Ref. 96, p. 123 by cautesy of Plenum Press)...

Figure 2.8 CVD coatings on cemented carbide substrates, (a) Single layer TiC coating, 8 pm thick (b) Multilayer TiC/TiCN/TiN coating, —10 xm total thickness, and (c) TiCN coating supporting multiple alternating coating layers of A1203 and TiN. (Adapted from Ref.

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