Material Dissolution

The model described in Section 7.1 suggests that once material is abraded from the copper surface, it must be removed 

The surface profile of a copper line formed by CMP in a slurry of 1 vol% K Oj plus alumina abrasive and 1 vol% HNO3. The flat profile of the cqrper line is indicative of copper dishing due to chemical etching. The sample received approximately no overpolish. 

A second possibility is that the dislodged fragments could be adsorbed onto the abrasive particles surfaces. According to Cook, this removal mechanism dominates in the CMP of SiOz (Section 4.2). If such a deposition process does not significantly affect the abrasive particle size, suspension behavior, or abrasive 

In a third removal mechanism, the abraded material is swept away from the copper surface by the turbulent motion of the slurry. Assurances must be made that the abraded material does not return to the copper surface at a later point in the process. If the pad has long fibers, the abraded material may fall into the pad where it is held away from the surface. In an HjO only slurry, the presence of precipitates is indicated by the black color of the slurry during CMP. When polishing with a napped cloth comprised of long 

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In the electrolytic process of dissolution, an electric current is imposed on a solid, and this technique can bring about its dissolution in the liquid with which it is in contact. For example, if nickel sulfide is connected to a direct current source such that it becomes the anode and the cathode is any conducting material, dissolution will occur according to the following overall anodic reaction ... 

It consists in a deposition of ions from an electrolyte onto the cathode in an electrolytic cell, under the influence of an applied potential. Usually the process is accompanied by material dissolution from the anode. The electrowinning from aqueous solutions is an important commercial method for the production (and/or refinement) of many metals, including, for instance, chromium, nickel, copper, zinc. As for the electrodeposition from non-aqueous solutions, the primary production of aluminium, electrodeposited from a solution of A1203 in molten cryolite, is a typical example. Other metals which may be regularly reduced in a similar way are Li, Na, K, Mg, Ca, Nb, Ta, etc. 

The use of ISEs in non-aqueous media(for a survey see [125,128]) is limited to electrodes with solid or glassy membranes. Even here there are further limitations connected with membrane material dissolution as a result of complexation by the solvent and damage to the membrane matrix or to the cement between the membrane and the electrode body. Silver halide electrodes have been used in methanol, ethanol, n-propanol, /so-propanol and other aliphatic alcohols, dimethylformamide, acetic acid and mixtures with water [40, 81, 121, 128]. The slope of the ISE potential dependence on the logarithm of the activity decreases with decreasing dielectric constant of the medium. With the fluoride ISE, the theoretical slope was found in ethanol-water mixtures [95] and in dimethylsulphoxide [23], and with PbS ISE in alcohols, their mixtures with water, dioxan and dimethylsulphoxide [134]. The standard Gibbs energies for the transfer of ions from water into these media were also determined [27, 30] using ISEs in non-aqueous media. 

The mechanism of silicon etching in alkaline solutions is a process of material dissolution with a simultaneous hydrogen evolution. The main soluble product is a silicic anion Si02(0H)2 that can further be condensed to form polysilicic anions. In fact, due to the acido-basic ionization of OH radicals in a highly alkaline solution, Eq. (19) should be modified as follows ... 

Nearly all metals are thermodynamically unstable in most environments and the result of this instability is corrosion, such as oxidation or some other reaction with the environment. In both "wet" and "dry" corrosion three general phenomena occur. First, material from the metal can dissolve in the environment. This takes forms such as evaporation and volatile compound formation at high temperatures and material dissolution in aqueous solutions. Material loss by such processes may weaken a structure or cause loss of a protective layer. Second, a reaction layer may form on the surface of the metal. Frequently, these layers reduce the rate of a reaction and thus protect the material (passivate a... 

Discrete OH" ions exist only in the hydroxides of the more electropositive elements such as the alkali metals and alkaline earths. For such an ionic material, dissolution in water results in formation of aquated metal ions and aquated hydroxide ions ... 

Quite recently oxonium compounds of d-block transition metals and also closely related complexes of the lanthanides were isolated for the first time. In general, the solvent is aHF, and a strong Lewis acid, preferably AsFs, is added to the solution or suspension of an appropriate metal compound. Water may be introduced in various ways, e.g. using hydrated starting material, dissolution of metal oxides or even through the addition of H-.OAsFg. Some examples of reactions leading to new oxonium fluorometallates are collected in Table 4. 

Hypothesis 2. Diffusion of DOC and sulfate from confining bed pore waters provides sources of electron donor (organic carbon) and electron acceptor (sulfate). Carbon dioxide produced by this reaction drives shell material dissolution/ calcite cement precipitation which can explain the major ion and carbon isotope composition of Black Creek aquifer water. 

The mass balance implied by hypothesis 3 is shown in Table 10. The net result of the assumptions built into this model is to decrease the amount of organic matter oxidized to carbon dioxide and to increase the amount of DIC from shell material dissolution. This, in turn, decreases the amount of shell material dissolution/calcite cement precipitation needed to achieve isotope balance. Between Olanta and MRN-77, the amount of dissolution/precipitation needed for isotope balance is 2.0 mmol CaC03 kg of H2O, and 25 mmol CaC03 from MRN-77 to HO-338. This, in turn, implies that l-13vol.% of the aquifer would be cemented by calcite, which is roughly in line with observed calcite cementation. 

Synthesis of Giant Zeolite Crystals by a BMD (Bulk Material Dissolution) Technique In 2001, Shimizu et al.[120] developed a BMD (bulk materials dissolution) technique for the synthesis of giant zeolite crystals based on others work. A piece of bulk material,... 

S. Shimizu and H. Hamada, Synthesis of Giant Zeolite Crystals hy a Bulk Material Dissolution Technique. Microporous Mesoporous Mater., 2001, 48, 39-46. 

Acid Dissolution. In view of the fact that the oxides of two transition metals, Fe and Mn, account for 65% of the mass of the tungsten ore tailings, acids are the obvious choice for material dissolution. It was found that concentrated HCl dissolves up to 80% of the total mass, including nearly all of the Fe, Mn, and Sc content, leaving behind a residue which is quite different in nature. While the starting material is black, soft, and fairly reactive, the insoluble residue obtained from the acid digestion, the so-called acid residue, is much lighter in color, sandy in texture, and unreactive. It contains primarily W, Si, Nb, Ta, and other acid-insoluble constituents. 

The linear dependence of the material dissolution on acid concentration at fixed reductant concentration. 

Figure 1. Tombstones of similar varieties of marble. (a) unexposed to atmospheric conditions and (b) exposed for 65 years at Arlington National Cemetery, Arlington, VA. Comparison of engraved inscriptions shows the extent of material dissolution caused by exposure (names of individuals were manually removed).

The important chemical processes which can occur in the coolant are radiolytic decomposition to produce oxygen, corrosion of the system materials, dissolution of the metal oxides so formed, deposition of corrosion products on the system surfaces, and transport of radioactive nuclides generated within deposits on the fuel sheaths. The major sys-... 

P-26 - Direct conversion of bulk-materials into MFI Zeolites by a bulk-material dissolution technique... 

Bulk-material dissolution in MFI synthesis 02-P-26 Butadiene dehydrocyclodimerisation 22-0-03... 

Synthesis, clear solution 02-0-02 02-P-29 20-P-16 Synthesis, MFI, bulk-material dissolution 02-P-26 ... 

Potassium hydroxide is noncombustible. However, mixing it with water can produce sufficient heat to ignite combustible materials. Dissolution in water is exothermic due to the formation of hydrates. Neutralization with acids is exothermic, which may become violent if large amounts in high concentrations are mixed rapidly. 

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