Plating of metals

Uses. Propargyl alcohol is a component of oil-well acidizing compositions, inhibiting the attack of mineral acids on steel (see Corrosion and CORROSION control). It is also employed in the pickling and plating of metals. 

Electrodeposition of Metals. Citric acid and its salts are used as sequestrants to control deposition rates in both electroplating and electroless plating of metals (153—171). The addition of citric acid to an electroless nickel plating bath results in a smooth, hard, nonporous metal finish. 

E. Peadsteia and H. E. BeUis, Electroless Plating of Metals, American Electroplaters Society, Wiater Park, Ela., 1972. 

Yourfacility is involved in chrome plating of metal parts, which produces an aqueous plating waste that is treated on-site to recover chromium sludge. The effluent from the on-site treatment plant, which contains chromium compounds (a listed toxic chemical), is piped to a POTW. The chromium sludge is transferred to an off-site, private ly owned firm tor the recovery of the chromium. 

A simple model of the e.d.l. was first suggested by Helmholz in which the charges at the interface were regarded as the two plates constituting a parallel plate capacitor, e.g. a plate of metal with excess electrons (the inner Helmholz plane I.H.P.) and a plate of excess positively charged ions (the outer Helmholz plane O.H.P.) in the solution adjacent to the metal the... 

After special pretreatments, specific grades of plastics can be put through electroplating processes similar to those used in the plating of metals. Electroplated plastic products are very durable and provide... 

Figure 14 illustrates a simple ionization circuit consisting of two parallel plates of metal with an air space between them. The plates are connected to a battery which is connected in series with a highly sensitive ammeter. 

At the bottom of the pack the polymer exits into the air via a multiplicity of small holes through a thick plate of metal (the spinneret). The number of holes can... 

A second class of membranes are described as dense membranes. They may consist of thin plates of metals (Pd and its alloys, Ag and some alloys) or oxides (stabilized zirconia or bismuth oxides, cerates). These membranes are permeable to atomic (for metals) or ionic (for oxides) forms of hydrogen or oxygen and have been studied, especially, in conjunction with chemical... 

The best-known use of chromium is for the plating of metal and plastic parts to produce a shiny, reflective finish on automobile trim, household appliances, and other items where a bright finish is considered attractive. It also protects iron and steel from corrosion. 

The most efficient system devised by Monsanto uses electrodes fabricated from carbon steel plate, electro-coated on one face with cadmium. These are stacked in parallel so that the electrolyte can be pumped through the gap between successive plates. Overall tire system forms a series of electrochemical cells with a cadmium cathode and a carbon steel anode. Each plate of metal forms the cathode of one cell and the anode of the next in the stack. Electric current is passed across the stack. The electrolyte contains phosphate and borate salts as corrosion inhibitors, EDTA to chelate any cadmium and iron ions generated by corrosion together with hex-amethylenebis(ethyldibutylammonium) phosphate to provide the necessary telraal-kylammonium ions. This electrolyte circulates through the cell from a reservoir and there is provision for the introduction of acjylonitrile and water as feedstock. The overall cell reaction is ... 

The protective surface treatment of solids such as the plating of metals. 

In plating of metals a film of metal such as chromium is deposited from a salt solution onto a reactive metal electrochemicaUy,... 

Hydrazine reduces heavy metal oxides and their salts to free metals. These reactions are utilized for plating of metal films on plastics and glass ... 

Philalethes says, in A Brief Guide to the Celestial Ruby. "The Philosopher s Stone is a certain heavenly, spiritual, penetrative, and fixed substance, which brings all metals to the perfection of gold or silver (according to the quality of the Medicine), and that by natural methods, which yet in their effects transcend Nature.. . Know then that it is called a stone, not because it is like a stone, but only because, by virtue of its fixed nature, it resists the action of fire as successfully as any stone. In species it is gold, more pure than the purest it is fixed and incombustible like a stone, but its appearance is that of very fine powder, impalpable to the touch, sweet to the taste, fragrant to the smell, in potency a most penetrative spirit, apparently dry and yet unctuous, and easily capable of tinging a plate of metal. If we say that its nature is spiritual, it would be no more than the truth if we described it as corporeal, the expression would be equally correct."... 

Lead ores are widely distributed in Nature, and are easily smelted. The Babylonians too engraved inscriptions on thin plates of metallic lead (10). The Romans used it extensively for water pipes, writing tablets, and coins. Unfortunately, they also used it for cooking utensils, and lead poisoning was an all-too-frequent result. A few very small lead nuggets, some of which are believed to be of pre-Columbian origin, have been found in Peru, Yucatan, and Guatemala (41). 

Preparation of Tin by Reduction with Zinc. Immerse a plate of metallic zinc into a tin(II) chloride solution. What happens Write the equation of the reaction. 

The first candidate is an inorganic mineral formed either by chemical processes or through some form of biomineralization. The latter development may have been an evolutionary response by the cellular material to improve on its coincidental use of an existing mineral structure. The previous examples all presume a cell, or cell model, with a flexible outer membrane composed of a water impermeable material such as a lipid or phospholipid. However, as mentioned at the start of this chapter it is possible to form capsules from materials that are rigid solids. In Nature the best examples of these are algae that form plates of metal carbonates, coccoliths, and... 

It is well known that a hot plate of metal will cool faster when placed in front of a fan than when exposed to still air. We say that the heat is convected away, and we call the process convection heat transfer. The term convection provides the reader with an intuitive notion concerning the heat-transfer process however, this intuitive notion must be expanded to enable one to arrive at anything like an adequate analytical treatment of the problem. For example, we know that the velocity at which the air blows over the hot plate obviously influences the heat-transfer rate. But does it influence the cooling in a linear way i.e., if the velocity is doubled, will the heat-transfer rate double We should suspect that the heat-transfer rate might be different if we cooled the plate with water instead of air, but, again, how much difference would there be These questions may be answered with the aid of some rather basic analyses presented in later chapters. For now, we sketch the physical mechan-... 

Electrolytic plating of metals is performed for both protective and decorative reasons. The arrangement and chemistry of the plating bath must be such that a coat of even thickness, non-porous, adherent metal is produced. The "throwing power is a measure of the ability of the metal ions to reach remote sections of the article to be plated. Accurate control of current, potential, plating bath chemistry, and temperature is essential in order to obtain high-quality results. 

Platen. A flat plate of metal which transmits the pressure of a hydraulic press to the object being pressed. 

BRACTEAE LAMINAE — Larger plates of metal an instrument like the sole of a shoe. BRACTEAE FERREAE — Plates of iron. 

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