Watt s bath

Ten mmoles of S-trifluoromethyl trifluoromonothioperoxyacetate are photolyzed for hour through Pyrex glass with a Hanovia Utility ultraviolet quartz lamp (140 watts), which produces bis(trifluoromethyl) sulfide and carbon dioxide quantitatively. Pure bis(trifluoromethyl) sulfide is retained in a —120°C. slush bath (diethyl ether) while carbon dioxide slowly sublimes into a —183°C. bath during trap-to-trap distillation. 

The reactor consisted of a quartz tube (12 in. long, 1/2 in diameter) and was heated by a 1200 watt furnace with a feed back temperature controller. The catalyst was placed in powder form on a porous frit, and its temperature was measured by a chrome1 Alumel thermocouple inserted into a thermowell. The reactor inlet and outlet compositions were measured by an on line gas chromatograph (G.C.) equipped with an 18 ft long, 1/8 in O.D column filled with 80/100 Porapak S and operated at 115°C using He as a carrier gas. An ice bath, placed between the reactor exit and the G.C. sampling valve, condensed the steam and removed the water. 

The excellent adherence of Cu layers gives the opportunity of preparing electroplated adherent films of various metals onto n-Si(lll), using a two step process in which Cu clusters are first grown as precursors and then, the metal of interest is plated. Figure 5 shows an in plane TEM view of Cu clusters electrodeposited on n-Si(lll) (Vd = -1.75 V, td = 40 s). They represent the minimum quantity of copper necessary to obtain nickel films from a modified Watts bath (pH 3). Nickel was electrocristallized at Vd = - 1.30 V and we emphasize that it was not possible to achieve Ni deposition on n-Si(lll) at this potential without the presence of Cu clusters. Ni films are also very adherent and they successfully passed the... 

S.4.2.3 Nickel-phosphorus Excellent corrosion protection is observed if the nickel layer contains phosphorus. This was first observed with electroless NiP layers (see Sect. 5.5.4.2.4). During the last years, electrochemical plating processes for nickel phosphorus have been developed. In these processes, a phosphorus source has to be added to the electrolyte either sodium phosphite or sodium hypophosphite are used. The other components of the electrolyte are similar to a Watts bath (see Sect. 5.S.4.2). Table 6 lists a typical composition. 

K. S. Willson and J. A. Rogers, Orientation, Crystal Structure and Appearance of Nickel Deposits from a Watts Bath Containing Coumarin, Tech. Proc. American Electroplaters Society. Vol. 51,1964, 92-95. 

For nickel deposition from a Watts bath (a weakly acidic bath containing sulphate and chloride), two types of brightener are recognized. The first are aromatic sulphones or sulphonates and they lead to bright deposits without lustre and also reduce stress. The second are molecules containing —C=N, N—C=S or C=0 entities, e.g. thiourea and coumarin, which produce deposits with a high lustre but also raise the stress and brittleness in the metal. In practice both types are used in combination. The aromatic sulphonates are also brighteners for tin or copper. 

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