Changes of stainless steels surface morphology as a result of interaction with intense pulsed plasma beams containing ions of rare earth elements
Stainless steels are used in numerous industrial applications, mainly due to their excellent corrosion resistance. However, in many cases their low hardness and poor tribological properties impose strong limitations. On the other hand, there are many examples that require the use of electrolyte corrosion and high temperature corrosion resistant materials, which at the same time exhibit good wear resistance. Examples of such applications include liquid flow sensors, temperature, pressure and humidity sensors for aggressive environments, interconnectors for solid oxide fuel cells (SOFC) etc. In all these cases stainless steels are frequently used. The beneficial effect of active elements with high oxygen affinity, such as yttrium, cerium, lanthanum and other rare earth elements (REE) on high temperature oxidation resistance and corrosion resistance against aggressive media has already been studied, e.g. [1, 2]. In addition, these elements added to the bulk alloys or to their surfaces dramatically improve the oxide scale adherence [4]. On the other hand, it is known from our recent study that the surface modification process using intense plasma pulsed leads to improvement of the tribological properties of unalloyed steels [5–7]. Pulsed-plasma treatment – a procedure developed at the Soltan Institute for Nuclear Studies (SINS) Świerk, Poland, consists in treating a solid with plasma pulses of Changes of stainless steels surface morphology as a result of interaction with intense pulsed plasma beams containing ions of rare earth elements Bozena Sartowska, Jerzy Piekoszewski, Lech Waliś, Elzbieta Skladnik-Sadowska, Marek Barlak
Effect of minor elements and a Ce surface treatment on the oxidation behavior of an Fe–22Cr–0.5Mn (Crofer 22 APU) ferritic stainless steel
Abstract This paper details the oxidation behavior of coupons from three different Crofer 22 APU sheets. Oxidation tests were conducted at 800 ∘ C in moist air for 2300 h. The major features of the scales were similar in all three coupons, with a continuous Cr–Mn spinel layer forming at the gas–oxide interface and a Cr2O3 layer forming at the oxide–metal interface. Also, at the Cr2O3–metal interface, large Cr–Mn oxide particles formed in the base metal. Metal extrusions in the oxide scale were observed in the vicinity of these Cr–Mn oxide particles. All three alloys had internal oxide particles forming in the base metal beneath the oxide scale, and the extent of this internal oxidation was related to the Al and Si-content in the coupons (as also reported by Piron-Abellan J, Huczkowski P, Ertl S, Shemet V, Singheiser L, Quadakkers W. In: Fuel cell seminar, 2004. San Antionio, TX, November 1–5, 2004). Of note, discontinuous Ti-oxide and Mn-oxide particles formed above the outer spinel layer on the coupons with relatively high Al and Si contents. The effectiveness of rare-earth surface modification on improving oxidation resistance of this alloy was demonstrated. Pack cementation-like processes were used to treat the surface of the coupons with Ce. A continuous Cr–Mn outer oxide layer and a continuous inner Cr2O3 layer formed on the surface of the treated coupons during oxidation. However, the thickness of the scales and amount of internal oxidation were significantly reduced with the treatment, leading to the decrease in oxidation rate. The amount of internal oxidation was also reduced with the treatment. The treatment appeared to suppress the formation of SiO2 at the scale–metal interface in high Si containing alloys. ASR measurements indicate that the treatment decreases the electrical resistance, which is a benefit for SOFC interconnect application.
Euthanasia — again: “Letting die” is not in the patient's best interests: a case for active euthanasia
Recent discussions in the Journal on the subject of euthanasia have relied on intuitive appeals to distinctions traditionally considered to be morally relevant, such as the distinction between acts and omissions (or killing and letting die), or ordinary and extraordinary means of treatment. These discussions remained inconclusive. However, the question of euthanasia no longer remains inconclusive if one adopts the perspective suggested by the United States President's Commission for the Study of Ethical Problems in Medicine and Biomedical and Behavioral Research and by the World Medical Assembly – that a doctor should act in his or her patient's best interests. From this vantage point, it is argued, there will be instances when active euthanasia is the proper cause of action.