Plate out

The term refers to the deposition of pigment on the surface of the processing equipment or on the system itself. In contrast to similar phenomena caused by blooming, plate-out does not reappear once the pigment film is rubbed off. 

Conditions to be avoided are high temperatures and high pigment concentration, both of which increase plate-out effects. 

Kampf method [54] or the adhesives technique [55], both of which also lend themselves to the analysis of degraded paint films. 

Similar phenomena are observed in enamels which contain certain organic pigments, but it should be noted that the chemical and micromorphological processes that are responsible for this form of molecular degradation are not known. 

The effect of chalking is rapid and marked even after a short weathering time. There appears to be no clear distinction between chalking in the broader sense of the word and plate-out the two phenomena are very much related. As in plate-out and unlike in blooming, the particles that adhere to the polymer surface through chalking can be removed comparatively easily without reappearing. 

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Permeable intervals can be identified from a number of logging tool measurements, the most basic of which is the caliper tool. The caliper tool is used to measure the borehole diameter which, in a gauge hole, is a function of the bit size and the mudcake thickness. Mudcake will only build up across permeable sections of the borehole where mud filtrate has invaded the formation and mud solids (which are too big to enter the formation pore system) plate out on the borehole wall. Therefore the presence of mudcake implies permeability. 

Oligomeric Flame Retardants. There are several oligomeric flame retardants. The principal advantage claimed for these materials is their resistance to bloom and plate-out. In some cases they are used at levels high enough that the resulting flame-retarded resia should properly be viewed as a polymer blend or alloy. AH of the available oligomeric flame retardants are brominated (Table 6). 

Commercial Stabilizers. There is a great variety of commercial formulations utilizing the mixture of the alkaU and alkaline-earth metal salts and soaps. In many cases, products are custom formulated to meet the needs of a particular appHcation or customer. The acidic ligands used ia these products vary widely and have dramatic effects on the physical properties of the PVC formulations. The choice of ligands can affect the heat stabiHty, rheology, lubricity, plate-out tendency, clarity, heat sealabiHty, and electrical and mechanical properties of the final products. No single representative formulation can cover the variety of PVC appHcations where these stabilizers are used. 

If the cations in solution are condensable as a soHd, such as copper, they can plate out on the cathode of the cell. As the same time, perhaps some hydrogen is also produced at the cathode. The SO can react with a copper anode material by taking it into solution to replace the lost copper ions. Thus the anode is a consumable electrode in the process. 

Electroplating. Aluminum can be electroplated by the electrolytic reduction of cryoHte, which is trisodium aluminum hexafluoride [13775-53-6] Na AlE, containing alumina. Brass (see COPPERALLOYS) can be electroplated from aqueous cyanide solutions which contain cyano complexes of zinc(II) and copper(I). The soft CN stabilizes the copper as copper(I) and the two cyano complexes have comparable potentials. Without CN the potentials of aqueous zinc(II) and copper(I), as weU as those of zinc(II) and copper(II), are over one volt apart thus only the copper plates out. Careful control of concentration and pH also enables brass to be deposited from solutions of citrate and tartrate. The noble metals are often plated from solutions in which coordination compounds help provide fine, even deposits (see Electroplating). 

Fig. 11.3. Microstructures during the slow cooling of a eutectoid steel from the hot working temperature. As a point of detail, when peorlite is cooled to room temperature, the concentration of carbon in the a decreases slightly, following the a/a + FejC boundary. The excess carbon reacts with iron at the or-FejC interfaces to form more FejC. This "plates out" on the surfaces of the existing FejC plates which become very slightly thicker. The composition of Fe3C is independent of temperature, of course.

The effect on lubrication, printing, heat sealing and plate-out. 

Somewhat better results have been obtained with octoates and benzoates but these still lead to some plate-out. The use of liquid cadmium-barium phenates has today largely resolved the problem of plate-out whilst the addition of a trace of a zinc salt helps to improve the colour. Greater clarity may often be obtained by the addition of a trace of stearic acid or stearyl alcohol. Thus a modem so-called cadmium-barium stabilising system may contain a large number of components. A typical packaged stabiliser could have the following composition ... 

Will the pigment withstand processing conditions anticipated, i.e. will it decompose, fade or plate-out ... 

Milk-of-lime transfer pumps should be of the open impeller centrifugal type. Pumps having an iron body and impeller with bronze trim are suitable for this purpose. Rubber-lined pumps with rubber-covered impellers are also frequently used. Makeup tanks are usually provided ahead of centrifugal pumps to ensure a flooded suction at all times. Plating out of lime is minimized by the use of soft water in the makeup tank and slurry recirculation. Turbine pumps and eductors should be avoided in transferring milk of lime because of scaling problems. 

PORV operation, or rupture. A reactor is designed to accomodate these releases a keep the radioactivity confined. Even in a damaged state, a power plant affords a t< path for release and a large surface for plate-out. 

The amounts of material released from a damaged plant are usually expressed in fractions of the isotopic quantities in the core. These source terms (meaning source for the ex plant transport) depend on accident physics, amount of core damage, time at elevated temperatures, retention mechanisms, and plate-out deposition of material as it transports from the damaged core to release from containment. This section gives an outline of early source term assessments, computer codes used in calculations, and some comparisons of result.s. 

Avoid using copper-based compounds such as copper carbonate. Copper can plate out on steel and set up galvanic corrosion cells, resulting in accelerated corrosion of the steel. 

In this reaction, copper metal plates out on the surface of the zinc. The blue color of the aqueous Cu2+ ion fades as it is replaced by the colorless aqueous Zn2+ ion (Figure 18.1). Clearly, this redox reaction is spontaneous it involves electron transfer from a Zn atom to a Cu2+ ion. 

Oxidation of Ni by Cu2+. Nickel metal reacts spontaneously with Cu2+ ions, producing Cu metal and Ni2+ ions. Copper plates out on the surface of the nickel, and the blue color of Cu2+ is replaced by the green color of NP+. 

An electrolysis experiment is performed to determine the value of the Faraday constant (number of coulombs per mole of electrons). In this experiment, 28.8 g of gold is plated out from a AuCN solution by running an electrolytic cell for two hours with a current of 2.00 A. What is the experimental value obtained for the Faraday constant ... 

If you wish to replate a silver spoon, would you make it the anode or cathode in a cell Use half-reactions in your explanation. How many moles of electrons are needed to plate out 1.0 gram of Ag ... 

The general picture of the relative merits of homogeneous and heterogeneous processes has not yet emerged clearly. The homogeneous catalyst system may offer advantages in chemical efficiency but lead to difficulties of catalyst separation and recovery, or catalysts may tend to plate out in the reactor due to slight instability. Materials of construction may have to be different for the two rival plants. All these factors will have to be considered in an economic assessment and detailed studies made of the complete process networks in both cases. 

The periodic development and use of new steel alloys can improve ferrous corrosion resistance however, where economizer units are constructed of copper alloys, under certain conditions serious copper corrosion problems may result. This occurs when FW having a pH over 8.3 also contains small amounts of ammonia and dissolved oxygen (DO). The ammonia may be present, for example, as a result of the overuse or inappropriate application of certain amines. Further damage may occur from the plating-out of the copper-ammonia ion then created as a cathode on boiler tubes. This promotes anodic corrosion of the immediate surrounding anodic areas. 

Inadequate acid cleaning procedures also may introduce traces of copper into the boiler (typically originally present as copper-containing deposits), which can plate out onto clean metal surfaces and cause localized, anodic area pitting corrosion. 

The soluble copper ammonia ion passes through the condensate system and plates out as a cathode on steel surfaces in the deaerator, heaters, economizer, and the boiler itself. A secondary galvanic corrosion process is initiated that damages the surrounding steel by forming ferrous hydroxide and releasing copper and ammonia. The ammonia carries over into the steam, and the entire corrosion process repeats itself. 

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