Plate coating

Several appHcations have been found for bis(2-chloroethyl) vinylphosphonate as a comonomer imparting flame retardancy for textiles and specialty wood and paper appHcations. Its copolymerization characteristics have been reviewed (76,109). This monomer can be hydrolyzed by concentrated hydrochloric acid to vinylphosphonic acid, polymers of which have photoHthographic plate coating utiHty (see Lithography). It is also an intermediate for the preparation of an oligomeric vinylphosphonate textile finish, Akzo s Fyrol 76 [41222-33-7] (110). 

The existence of bismuthine was first demonstrated by using a radioactive tracer, Bi (8). Acid treatment of a magnesium plate coated with Bi resulted in the hberation of a volatile radioactive compound. In subsequent experiments, magnesium bismuthide [12048-46-3], Mg Bi, was treated with acid the yield, however, was only one part of bismuthine for every 20,000 parts of bismuth dissolved. Attempts to prepare bismuthine by reduction of bismuth trichloride with a borohydride have not been particularly successful. Experimental quantities ate best prepared by disproportionation of either methylbismuthine [66172-95-0], CH Bi, or dimethylbismuthine [14381-45-4], C2H. Bi (7) ... 

Other decoratively plated coatings produced in quantity are copper and copper alloys. Copper-plated hardware for cabinetry, lighting fixtures, household trim, and other uses is protected using a top coat of clear lacquer. Copper plating finishes are available with a variety of post-treatments to simulate antique or mstic appearances. 

J. Homer, Microhardness Testing of Plating Coatings Recent Round-Robin Experiences, ia Ref. 47. 

J. Homer, "Microhardness Testing of Plating Coatings Defining Precision and Bias," Inf/Tech Conf. Proc., AESF SUR/FIN, Atianta, Ga., 1992. 

The interactions between solute and the pha.ses are exactly the same as those present in LC separations, namely, dispersive, polar and ionic interactions. At one extreme, the plate coating might be silica gel, which would offer predominately polar and induced polar interactions with the solute and, con.sequently, the separation order would follow that of the solute polarity. To confine the polar selectivity to the stationai y phase, the mobile phase might be -hexane which would offer only dispersive interactions to the solute. The separation of aromatic hydrocarbons by induced polar selectivity could be achieved, for example, with such a system. 

Sprayed, vacuum-deposited and plated coatings can be applied to most metals and to many non-metals, e.g. vacuum deposition is applied to many substrates including plastics spray application can be used for coating fabric, plastic and paper. Hot dipping and other diffusion processes are dependent on the nature of the substrate for the properties of the coating. Most commercial applications of aluminium coatings are on iron and steel with smaller quantities applied to aluminium alloys and plastics. 

In practice the thickest zinc coatings can be obtained by hot-dip galvanising or spraying. Table 13.7 compares the essential aspects of each coating. Plated coatings can also be produced mechanically in a wide range of thicknesses as well as electrochemically. 

Paint applied to a suitably prepared zinc coating will last longer than would be the case if it were applied direct to iron or steel, and the need for repainting thus becomes less frequent. With hot-dip galvanised or zinc-plated coatings, however, it is necessary either to use special primers or to prepare the surface before painting. This is primarily because most oil-based paints react with the unprepared zinc surface to form zinc soaps resulting in poor adhesion. 

Fig. 6-4. Calculated curves showing relationship between intensity ratio and thickness for various values of exponent a. The abscissa scale is logarithmic. Circles = plated coatings squares = evaporated coatings. (Liebhafsky and Zemany, Anal. Chem., 28, 455.)...

Four pilot plant experiments were conducted at 300 psig and up to 475°C maximum temperature in a 3.07-in. i.d. adiabatic hot gas recycle methanation reactor. Two catalysts were used parallel plates coated with Raney nickel and precipitated nickel pellets. Pressure drop across the parallel plates was about 1/15 that across the bed of pellets. Fresh feed gas containing 75% H2 and 24% CO was fed at up to 3000/hr space velocity. CO concentrations in the product gas ranged from less than 0.1% to 4%. Best performance was achieved with the Raney-nickel-coated plates which yielded 32 mscf CHh/lb Raney nickel during 2307 hrs of operation. Carbon and iron deposition and nickel carbide formation were suspected causes of catalyst deactivation. 

The bed of parallel plates coated with Raney nickel catalyst was much more reactive than the bed of precipitated nickel. This was revealed by the generally lower CO concentration in the product gas during operation with the parallel plate bed for example, after 450 hrs stream time, it was 0.01% with the bed of sprayed Raney nickel (experiment HGR-14) and 0.05% with the bed of precipitated nickel catalyst (experiment HGR-13). 

The higher reactivity of the Raney nickel coated plates is also illustrated by the plots of catalyst temperature vs. bed length (Figure 10). The maximum bed temperature (indicative of near-completion of metha-nation) was consistently reached within a shorter distance from the gas inlet, and the slopes of the curves are correspondingly steeper for the more reactive bed of parallel plates coated with Raney nickel. 

Copper plates coated with TiB2 by CVD have shown good resistance to corrosion by sea water and erosion by sand.t ]... 

The balloon was removed briefly while aliquots were taken. The flask was flushed again with nitrogen and the balloon was then replaced. Thin-layer chromatographic analyses were carried out on glass plates coated with silica gel G which were purchased from Analtech, Newark, Delaware. With a 10 2 3 (v/v/v) solution of 1-butanol, acetic acid, and water as developing solvent, the Rf values for the product and L-cysteine hydrochloride are 0.19 and 0.25, respectively. 

Thin-layer chromatograms were run on plates coated with silica gel using 1 10 (v/v) ether-hexane as developing solvent. 

Only a rough description of this micro reactor was given (Figure 5.10), not disclosing all details [20]. A pair of iron plates coated with Pd catalyst is inserted in disk-type holders. Such a supported micro channel device is encased in a housing. 

The micro reactor consisted of a pair of iron plates coated with Pd catalyst placed on disk-type polypropylene holders [20]. This micro channel device was encased in a stainless-steel housing. The thickness of the catalyst layer was approximately 5.0 pm 10 mg catalyst was deposited per plate, so giving 20 mg in total. The specific surface area of the catalyst was 3.6 0.4 m g ... 

TLC plates coated with the layer of polar adsorbent should be prewetted with a nonpolar solvent, such as benzene or n-heptane (n-hexane), to prevent deactivation of the adsorbent surface and to avoid glue up as a result of the penetration of the pores by lipid molecules and other impurities (i.e., wax). 

Alternatively, an aqueous solution of sodium diethyldithiocarbamate (3.5%, 2 ml) or freshly prepared solution of dithizone in chloroform (0.1%, 10 ml) was added to sample A. The metal diethyldithiocarbamates (termed sample B) or metal dithizon-ates (termed sample C) thus formed were extracted in chloroform. The volume of chloroform extract was reduced to 1.0 ml. Aliquots (10 pi) each of sample B and sample C were chromatographed on plates coated with 0.25-mm layer of silica gel G using benzene -t methyl isopropylketone (50 1) and toluene -r chloroform (50 1), respectively, as mobile phases. Metal dithizonates were self-detected. The namral colored metal diethyldithiocarbamates were converted into brown spots by spraying... 

Coated plates stored Discard plates, coat a... 

Applications Sollinger and Sawatzki [793] have reported the use of TLC-Raman for routine applications, e.g. TLC of hydroxybenzenes (including hydro-quinone and pyrogallol) on conventional, silica gel and specific Raman-TLC plates (coated with spherical silica gel). Databases were used for identification of substances. Typical detection limits were in the low p,g region per application, Micro-Raman spectrometry has been employed in analysing TLC fractions from polymer additives within a detection limit... 

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