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Abstract Investigations on metal halide systems carried out by Knudsen effusion mass spectrometry in the period 1990-2014 are reviewed in the present paper.163 original papers were published focused on metal halides showing still considerable activity in this area. The fundamentals of the Knudsen effusion mass spectrometry method and thermodynamic background of the investigation are briefly reported. Data to the system studied, temperature ranges, Knudsen cell materials, vapor species identified in the equilibrium vapors and the thermodynamic properties obtained in the study are presented. The important issues of metal halide vaporization studies are briefly discussed and commented. The studies of the vaporization of metal halogens by Knudsen effusion mass spectrometry aimed firstly atthe determination of gaseous complexes species in the vapor and determination of its thermodynamic data like sublimation enthalpy etc. and secondly at the determination of negative ions formation and various ion-molecule equilibria reactions of metal halide systems. Many of the studied materials have a crucial role for modern technologies, for example metal halide lamps, hot corrosion caused by halide salts, phosphorus recovery technologies or gas assisted separation of lanthanides. The investigation of such systems gives information on mechanisms of vaporization, volatility of the systems under various conditions (temperature, pressure etc.), reactivity, thermal stability, resistance etc. that could be further applied for various calculations and to predict the behavior of various components under various technological aspects.
One of the alternative renewable fuels is biomass but it is a difficult fuel because of its diversity and complexity. It can contain high percentages of K and Cl responsible for corrosion together with sand that have additionally an abrasive effect during combustion. Because of permanently extending the surface reaction due to abrasion the corrosion of the materials increases. In particular in power plants, the superheater tubes are exposed to a corrosive abrasive attack that is one of the main sources of concern. The development of new alloys for multilayer surface, which combines corrosive and abrasive resistance is therefore of high importance. Those new technical approaches must be at the same time cost-effective to be an alternative to conventional materials. The aim of the presented investigation methods is to test and develop suitable alloys for coatings for the super heater tubes of biomass power plants. First results of abrasion investigations show improved abrasion resistance compared to the multi-component reference material Alloy 625.
The environmental concerns about availability of fossil fuels and greenhouse gas effect increase and alternative renewable fuels for power plants are gaining significantly of importance. One of the alternative renewable fuels is biomass but it is a difficult fuel because of its diversity and complexity. It can contain high percentages of K and Cl responsible for corrosion together with sand that have additionally an abrasive effect during combustion. Because of permanently extending the surface reaction due to abrasion the corrosion of the materials increases. In particular in power plants, the superheater tubes are exposed to a corrosive abrasive attack that is one of the main sources of concern. The development of new alloys for multilayer surface, which combines corrosive and abrasive resistance is therefore of high importance. Those new technical approaches must be at the same time cost-effective to be an alternative to conventional materials. This paper presents the principle of experimental methods developed for the investigations of high temperature corrosion combined with abrasion in thermochemical processes with high hydrochloric acid concentrations like during biomass combustion. The aim of the presented investigation methods it to test and develop suitable alloys for coatings for the super heater tubes of biomass power plants. First results of abrasion investigations show improved abrasion resistance compared to the multi-component reference material Alloy 625.