Photoinduced reactivity of titanium dioxide

Understanding chemical reactions between carbons and NaOH and KOH: An insight into the chemical activation mechanism

Grain refinement of aluminium and its alloys is common industrial practice. The field has been extensively investigated by many workers over the past 50 years, not only to develop efficient grain refiners for different aluminium alloys, but also to achieve an understanding of the mechanism of grain refinement. The present review confines itself to the literature on grain refinement by heterogeneous nucleation and alloying. Initially, the fundamentals of grain refinement by inoculants are outlined. The types of grain refiner, Al-Ti-B master alloys in particular, and their methods of manufacture are next discussed. The grain refining tests to assess the efficiency of the grain refiners and the grain refining behaviour of aluminium alloys are also discussed in brief. The performance of a grain refiner, as well as the response of an aluminium alloy to grain refinement, is influenced by the microstructure of the grain refiner as controlled by the process parameters involved in its preparation and the alloying elements present in the aluminium alloy. The roles of these factors, and particularly the roles of poisoning elements such as Si, Cr, Zr, Li, are reviewed. The paper also reviews the mechanisms of grain refinement, the fading and poisoning phenomena, and the trends in the development of new grain refiners for aluminium alloys containing poisoning elements.

Grain refinement of aluminium and its alloys by heterogeneous nucleation and alloying

A DRIFTS study of the formation of surface groups on carbon by oxidation

FTIR, IR, and XPS have been used to study the films formed on lithium in propylene carbonate solutions of ,, and . Over a range of conditions, the main components detected in the initial surface films were lithium alkyl carbonates . Another alkyl carbonate solvent, diethyl carbonate, was found to react with lithium to form lithium ethyl carbonate, . In addition to solvent reduction, XPS measurements gave indication of salt reduction reactions. , , and were reduced by lithium to form halide ions, which were detected on the lithium surface. Two possible mechanisms for the formation of alkyl carbonates are discussed. One is the nucleophilic reaction of propylene carbonate with basic species such as OH−, while the other involves one‐electron reduction of propylene carbonate by lithium metal, followed by free radical termination reactions. When high concentrations of water were present, lithium carbonate was formed by further reaction of the alkyl carbonates with water. On lithium surfaces without a mechanically stable surface film, such as those of lithium/mercury amalgams, the reduction reaction is believed to proceed by an overall two‐electron process, and the primary product is lithium carbonate.

https://iopscience.iop.org/article/10.1149/1.2100722/pdf

Identification of surface films formed on lithium in propylene carbonate solutions

This chapter discusses the experimental, theoretical, and empirical correlations between functional organic groups and the infrared spectrum. The application of infrared spectroscopy to the identification of inorganic compounds is less successful. In obtaining infrared spectra of inorganic solids, an experimental complication arises from possible chemical reaction between the inorganic compound and the infrared window material or support medium. The chapter presents many examples of spectra of inorganic compounds in the solid phase. The majority of these compounds are crystalline solids in which the crystallographic unit cell contains several polyatomic ions or molecules. Optical modes called lattice modes of vibration result from the motion of one polyatomic group relative to another within the unit cell. Lattice modes occur in the region 400–10 cm −1 and are characteristic of specific crystal geometry. They are used as fingerprints for an inorganic compound in much the same way as the internal modes of vibration of organic compounds are used in the region 4000–400 cm −1 .

Infrared spectra of inorganic compounds

Infrared spectra of inorganic compounds (3800-45cm[-1])

A small tube containing a solid sorbent is convenient to use for collecting and concentrating trace organics in ambient air and worker breathing zones. Many techniques for air sampling with solid sorbents, especially for the long term eight hour sample, are relatively new. It is necessary to have criteria to judge methods utilizing these techniques and to establish guidelines which are accurate and practical. Parameters which affect collection and recovery and information necessary to define, develop and evaluate a sampling method are discussed. Progressive steps for the development and validation of air sampling methods are recommended.

Ronald O. Kagel

Papers

Infrared spectra of inorganic compounds

Infrared spectra of inorganic compounds (3800-45cm[-1])

Criteria for the evaluation of methods for the collection of organic pollutants in air using solid sorbents

Infrared study of the surface dehydration of 1-(o-chlorophenyl) ethyl alcohol on γ-Al2O3