다중혈관 관상동맥 환자에서 y-문합을 이용하여 양쪽 내흉동맥만을 사용한 우회술의 조기 성적

The American Society for Testing and Materials (ASTM) is an independent organization devoted to the development of standards.

American Society for Testing and Materials

Ash-related issues during biomass combustion: Alkali-induced slagging, silicate melt-induced slagging (ash fusion), agglomeration, corrosion, ash utilization, and related countermeasures

A concentrating solar power (CSP) system converts sunlight into a heat source which can be used to drive a conventional power plant. Thermal energy storage (TES) improves the dispatchability of a CSP plant. Heat can be stored in either sensible, latent or thermochemical storage. Commercial deployment of CSP systems have been achieved in recent years with the two-tank sensible storage system using molten salt as the storage medium. Considerable research effort has been conducted to improve the efficiency of the CSP system and make the cost of electricity comparable to that of the conventional fossil-fuel power plant. This paper provides a comprehensive summary of CSP plants both in operation and under construction. It covers the available technologies for the receiver, thermal storage, power block and heat transfer fluid. This paper also reviews developments in high temperature TES over the past decade with a focus on sensible and latent heat storage. High temperature corrosion and economic aspects of these systems are also discussed.

Review on concentrating solar power plants and new developments in high temperature thermal energy storage technologies

The implications of chlorine-associated corrosion on the operation of biomass-fired boilers

The effects of chlorides, hydrogen chloride, and sulfur dioxide in the oxidation of steels below deposits

Chloridation and oxidation of iron, chromium, nickel and their alloys in chloridizing and oxidizing atmospheres at 400–700°C

This paper presents the analysis of corrosion damages of metallic materials after application in waste fired boilers. The first part gives a description of corroded metallic specimens, collected from different grate fired plants in Germany and it will provide the base information for thermodynamic calculations and laboratory experiments, described in the second part of the paper.

In deposits from boiler tubes of waste incinerators there are significant amounts of molten phases, consisting of calcium-, potassium- and sodium-sulfates and/or potassium- and sodium-chlorides containing heavy-metals like lead and zinc. These heavy-metals are decreasing the melting point of the deposits and severe corrosion occurs especially by the molten phase. A thermodynamic approach is given which describes the stability of chlorides with respect to sulfates in deposits from waste fired boilers. It is shown that in HCl-containing gases especially heavy-metal sulfates will react to corresponding volatile chlorides. In addition, laboratory experiments are presented on the effect of heavy-metal sulfates and chlorides in the corrosion of several metallic materials. The experiments were carried out beneath a CaSO4- K2SO4- Na2SO4- ZnSO4- PbSO4 salt mixture at 600 °C, beneath the heavy-metal chlorides PbCl2, ZnCl2 and also beneath a ZnCl2- KCl mixture at 300–600 °C. The results of these studies show clearly the strong corrosive effect of heavy-metal rich salt mixtures in the corrosion of steels and nickel-based alloys.

Salt melt induced corrosion of metallic materials in waste incineration plants

The effect of the alloying elements Al, Cr, Mn, Mo, Si and Ti on the corrosion behaviour of ferritic Fe-15Cr model alloys was studied in a N2/He-5 vol.% O2 gas mixture with and without additions of 500–1500 vppm HCl at 600°C. The main corrosion mechanism is “active oxidation”, characterized by the formation of volatile metal chlorides at the metal/oxide interface. Volatilization and subsequent conversion of the chlorides into oxides results in the formation of porous and poorly adherent oxide scales. Large mass gains were observed for Fe-15Cr, Fe-35Cr and Fe-15Cr with additions of 5 wt.% Ti, 10 wt.% Mn or 10 wt.% Mo. The specific morphology of the corrosion products depends strongly on the alloying elements. For the Fe-Cr alloys, a model for the formation of the scales, which are characterized by alternating dense and porous layers, is presented. The addition of 5 wt.% Si or Al to Fe-15Cr leads to much better corrosion resistance by the formation of protective Cr2O3/Al2O3-layers, however in the case of Al addition the behaviour depends strongly on the experimental conditions, as surface treatment and flow velocity. In Fe-15Cr-10Mo preferential removal of the more reactive metals Fe and Cr was observed resulting in a Mo-enriched porous metal zone underneath the metal-oxide interface. The effect of carbon on the corrosion behaviour was examined by addition of 0.3–0.8 wt.% C to the model alloys. Cr-rich M23C6-carbides were attacked preferentially while Mo-rich M6C-carbides are very stable relative to the matrix and the attack occurs in regions surrounding the carbides.



Der Einflus von Legierungselementen auf die chlorinduzierte Hochtemperaturkorrosion von Fe-Cr-Legierungen in oxidierender Atmosphare



Der Einflus der Legierungselemente Al, Cr, Mn, Mo, Si und Ti auf das Korrosionsverhalten ferritischer Fe-15Cr-Modellegierungen wurde in einer N2/He-5 vol.% O2 Gasmischung mit und ohne Zusatz von 500–1500 vppm HCl bei 600°C untersucht. Der wesentliche Korrosionsmechanismus ist die „aktive Oxidation“, bei der sich fluchtige Metallchloride an der Metall/Oxid-Grenzflache bilden. Verdampfen und anschliesende Umsetzung der Chloride in Oxide fuhrt zu porosen und schlecht haftenden Oxidschichten. Hohe Massenzunahmen wurden beobachtet bei Fe-15Cr, Fe-35Cr und Fe-15Cr mit Zusatzen von 5 gew.% Ti, 10 gew.% Mn oder 10 gew.% Mo. Die spezifische Morphologie der gebildeten Oxidschichten hangt stark von den jeweiligen Legierungselementen ab. Im Falle der Fe-Cr Legierungen wird ein Modell fur die Bildung der Oxidschichten, die aus abwechselnd kompakten und porosen Schichten bestehen, vorgestellt. Der Zusatz von 5 gew.% Si oder Al fuhrt zu stark verbesserten Korrosionswiderstanden durch die Bildung von schutzenden Cr2O3/Al2O3-Schichten; im Falle des Aluminiums ist dies allerdings kritisch abhangig von den experimentellen Bedingungen, wie Oberflachenbearbeitung und Stromungsgeschwindigkeit. Bei Fe-15Cr-10Mo wird eine bevorzugte Reaktion der reaktiveren Metalle Fe und Cr beobachtet, was zu einer Mo-angereicherten porosen Metallzone unterhalb der Metall/Oxid-Grenzflache fuhrt. Der Effekt von Kohlenstoff auf das Korrosionsverhalten wurde durch Zulegieren von 0,3–0,8 gew.% C zu den Modellegierungen untersucht. Cr-reiche M23C6-Karbide werden relativ zur Matrix bevorzugt angegriffen, wahrend Mo-reiche M6C-Karbide sehr bestandig sind und der Angriff bevorzugt in den umgebenden Metallbereichen erfolgt.

Michael Spiegel

Papers

The effects of chlorides, hydrogen chloride, and sulfur dioxide in the oxidation of steels below deposits

Chloridation and oxidation of iron, chromium, nickel and their alloys in chloridizing and oxidizing atmospheres at 400–700°C

Salt melt induced corrosion of metallic materials in waste incineration plants

The influence of alloying elements on the chlorine‐induced high temperature corrosion of Fe‐Cr alloys in oxidizing atmospheres

Thermodynamic and kinetic consideration on the corrosion of Fe, Ni and Cr beneath a molten KCl–ZnCl2 mixture