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
Modification of the near surface layer of carbon steels with intense argon and nitrogen plasma pulses
Abstract Series of carbon steels with various contents of carbon were irradiated with high intensity (5–6 J cm−2), short (μs range) nitrogen and argon plasma pulses. In all samples the near surface layer of the thickness in μm range was melted. The paper reports the results of investigation of changes induced by such treatment. The identified phases, profiles of retained nitrogen concentration, microhardness and wear resistance of the modified layer are presented and discussed.
Limitations on the Use of Surface Doping for Improving High-Temperature Oxidation Resistance.
For more than 50 years, scientists have studied the “magic dust” of high-temperature oxidation—certain oxygen active or “reactive” elements which, when added to alloys in small quantities, effect profound improvements in their oxidation resistance. In general, high-temperature oxidation resistance is achieved by the oxidation of one or more alloy components to form a dense, stable, slow-growing, external oxide layer, or ’scale” such as α-Cr 2 O 3 , α-Al 2 O 3 , or SiO 2 . When added properly, reactive elements have a beneficial effect on the formation and growth of both α-Cr 2 O 3 and α-Al 2 O 3 scales. A standard list of reactive element (RE) effects would include: (1) an improvement in scale adhesion or resistance to spallation, (2) a change in the scale growth mechanism, (3) a reduction in the oxidation rate, related to the change in mechanism, (4) a modification in the scale microstructure, and (5) in the case of alloys that form Cr 2 O 3 scales, an improvement in selective oxidation, meaning that a lower Cr concentration in the alloy is required to form and maintain an external Cr 2 O 3 scale.