High Intensity Pulsed Plasma Beams Research Articles

Formation of the Surface Layer with Improved Tribological Properties on Austenitic Stainless Steel by Alloying with REE Using HIPPB

Austenitic stainless steels with their very good corrosion resistance are used in industrial applications nuclear and petrochemical industries, pulp and paper chemical, food and chemical processing, biomedical industries and others. But poor tribological and mechanical properties of austenitic stainless steels limit their applications in engineering fields. AISI 316L steel was subjected to transient treatment using high intensity pulsed plasma beams HIPPB. The plasma pulses contained both ions/atoms of electrodes material: Ce, La or (Ce+La) and those of working gas. The pulse energy densities (3.0 J/cm2) were sufficient to melt the near surface layer of steel and introduce REE to the melted material. Heating and cooling processes were of non-equilibrium type.

Enrichment of AISI 316L Steel Surface Layer with Rare Earth Elements Using Ion Beams

Enrichment of AISI 316L steel surface layers with rare earth elements was carried out using two methods with ion beam applying. The rst one was the ion implantation with the doses in the range of 1 × 10 cm−2 up to 5 × 10 cm−2 where mishmetal (Ce+La) was used as the ion source. The second method was the high intensity pulsed plasma beams. The plasma pulses contained both ions/atoms of Ce+La from the electrodes material (mishmetal). The pulse energy densities (3 J/cm) were su cient to melt the near surface layer of the steel and introduce those elements into the surface layer. The aim of this work was to investigate the changes of stainless steel surface properties (morphology, rare earth elements concentration, presence of identi ed phases) after the rare earth elements addition with or without melting. Scanning electron microscopy, energy dispersion spectroscopy, and X-ray di raction analysis were used for initial and modi ed surface characterisation. Grazing-incidence X-ray di raction shows di erences in the identi ed phase presence in the modi ed surface layer connected with the modi cation method.

Alloying the near Surface Layer of Stainless Steel with Rare Earth Elements (REE) Using High Intensity Pulsed Plasma Beams (HIPPB)

Addition of some active elements such as yttrium, cerium, lanthanum and other rare earths elements (REE) to austenitic stainless steels helps to improve their high temperature oxidation resistance and tribological properties. The high intensity plasma pulses were used to introduce Ce and La into AISI 316L austenitic stainless steel. The plasma pulses contained both ions/atoms of Ce-La and those of the working gas. The pulse energy densities were sufficient to melt the near surface layer of the steel and introduce those elements into the surface layer. Scanning electron microscopy (SEM) as well as energy dispersion spectroscopy (EDS) was used during each one part of surface characterisation. Obtained results allowed us to make decision about directions of modified material successive investigations.

Improvement of tribological properties of stainless steel by alloying its surface layer with rare earth elements using high intensity pulsed plasma beams

Austenitic stainless steels are widely used in numerous industrial applications due to their excellent corrosion resistance. However some applications are limited in cases when due to low hardness and poor tribological properties of stainless steel wear is responsible for the durability of a given engineering component.In the present work we have undertaken an attempt to improve the wear resistance of AISI 316L steel by alloying its near surface region with rare earth elements—REE using high intensity pulsed plasma beams in so called deposition by pulse erosion (DPE) mode. Power density of pulses was 106–107W/cm2 with the pulse duration in μs range. Heating and cooling processes were of non-equilibrium type. The near surface layer—thickness in μm range—was melted and simultaneously doped with cerium and lanthanum. Various parameters of the process were set up to get level of doping between 0.3 and 2.8at.% REE.An improvement of tribological properties—linear wear and scratch resistance—with increasing REE concentration as compared to the initial material was observed.

Improvement of high temperature oxidation resistance of AISI 316L stainless steel by incorporation of Ce–La elements using intense pulsed plasma beams

It is well documented that adding some active elements (such as Y, Ce, La, Er, others) to austenitic stainless steels helps to improve their high temperature oxidation resistance. In the present work we report preliminary results of incorporation of Ce and La into austenitic stainless steel AISI 316L using a new approach based on high intensity pulsed plasma beams. The characteristic feature of this approach relies upon the fact that incorporation of Ce–La occurs in the transiently melted near-surface layer of the substrate. Improving the near surface layer properties was connected with two facts: (i) material melting and cooling with very high rate and (ii) incorporation Ce–La to the molten phase. Modified samples were oxidized at 1000 °C for 80 h in air at atmospheric pressure. The obtained effects were similar to those observed in chromia-forming alloys doped by other conventional surface treatment techniques: oxide scales formed on the treated samples were more fine-grained, compact and adhered better than those formed on the un-treated samples, whereas the protective layer was produced closer to the surface.

The influence of distribution of titanium alloyed into carbon ceramics by the intense plasma pulses on their surface wettability with liquid copper

The paper presents an analysis of wettability and structural properties of the near surface layer of carbon ceramics into which titanium atoms were alloyed using a new method based on the use of high intensity pulsed plasma beams. The influence of various parameters of ceramic pre-treatment process on their wettability with liquid copper is presented and discussed. The information obtained can be useful in designing the ceramic–metal joints and composites.

Critical currents density and current loops range in MgB 2 thin layers obtained by the technique of ions implantation followed by pulsed plasma transient annealing

We report on the measurements of transport and magnetic properties of MgB 2 thin films obtained using ion implantation technique followed by irradiation with high intensity pulsed plasma beams. To get detailed information about the process of current percolation in a superconducting phase, about current transport and size of the current loop, we used the method of reverse leg of magnetisation loop. On the basis of this method we have found that the technique of implantation allowed one to obtain a continuous layer of MgB 2 superconductor characterized by the critical current density of J c = 1.25 × 10 5 A/cm 2.

Corrosion resistant Ti-Pd surface alloys produced by high intensity pulsed plasma beams: Part 1. Deposition by pulsed erosion and vacuum evaporation/pulsed implantation doping modes

Electron beam processing is an efficient technology to reduce emissions of pollutants from flue gases of industrial plants. The present study examines the use of high intensity pulsed plasma beams for surface alloying of the electron-transparent, titanium foil window, through which electrons enter into the flue gas, with the purpose of increasing its resistance to corrosion. The surface alloying, with palladium, to depth of a few hundred nanometres, is carried out under two modes of operation of a rod plasma injector: pulsed implantation doping (PID) and deposition by pulsed erosion (DPE) modes, using nitrogen as the working gas. The performance of the resultant alloys is evaluated in 0.1 M H 2SO 4 at 80 °C. The corrosion resistance of the titanium foil is substantially improved by the surface alloying, with a shift in the open-circuit potential of the treated foil toward the region of passivity of titanium. Corrosion rates were slightly lower for the DPE mode of alloying than for the PID mode. The changes in surface regions of the alloyed layers following immersion in the test environment were determined by analytical scanning electron microscopy, Rutherford backscattering spectroscopy, nuclear reaction analysis and medium energy ion scattering revealing morphologically and compositionally non-uniform alloys and losses of palladium.

Corrosion resistant Ti–Pd surface alloys produced by high intensity pulsed plasma beams: Part II. Deposition by pulsed implantation doping mode with palladium implantation using a MEVVA source

Surface alloys of Ti–Pd have been produced on titanium foils using high intensity pulsed plasma beams in the pulsed implantation deposition mode, with nitrogen as the plasma gas. Unlike in previous work, the palladium was initially introduced into the titanium foil by ion implantation using a metal vapour vacuum arc (MEVVA) source. The corrosion resistance of the alloys was examined by exposure to 0.1 M H 2SO 4 solution at 80 °C. This environment has been employed previously to evaluate surface treatments for improving the corrosion resistance of titanium foils used in electron beam technology for removal of pollutants from flue gases. The foils reveal high corrosion resistance relative to untreated titanium. The improved behaviour is associated with the shift of the open-circuit potential into the range of passivity of titanium. During exposure to the test solution, palladium is enriched at the alloy surface, with generation of nanoparticles in association with anatase and possibly amorphous titania. The formation of the nanoparticles in a weakly adherent surface layer results in some loss of the palladium.

Excimer laser surface alloying of titanium with nickel and palladium for increased corrosion resistance

In the electron beam treatment of flue gases, titanium foil is employed as an electron-transparent window. Due to its degradation in the flue gas environment and eventual failure, extension of the life of the window is being sought. Previous studies have indicated significant improvements of corrosion resistance from surface alloying with nickel or palladium, using high intensity pulsed plasma beams, but restricted size of vacuum systems prevents treatment of large surfaces. In the present work, an excimer laser was employed to surface alloy titanium foil with nickel or palladium, using fluences in the range 0.4–1.1 J cm −2 and either nitrogen or argon as the cover gas. The resultant surfaces provided high resistance to corrosion in 0.1 M H 2SO 4 solution at 80 °C that simulates, under accelerated conditions, the degradation of titanium by the flue gas. The improved behaviour is associated with the corrosion potential being shifted to the region of passivity. Treatments at increased fluences reduced losses of nickel and increased alloying of palladium during processing of the foils. Palladium was largely retained during the subsequent immersion tests, contrasting with the depletion of nickel by corrosion that limits the durability of the treated foils. The corrosion rates of the optimum palladium-alloyed surfaces were about two orders of magnitude lower than that of untreated titanium.

Modification of titanium surface by its alloying with silicon using intense pulsed plasma beams

Surface alloying of Ti with Si has been performed with the use of high intensity pulsed plasma beams. In this technique, short, intense (1 μs, 3–4 J/cm 2) plasma pulses serve as a source of heat to melt the near surface layer (up to 2 μm) of the Ti substrate together with a Si film (30 and 70 μg/cm 2) pre-deposited on it. In the molten state, lasting a couple of microseconds, rapid diffusion of Si into Ti occurs leading to formation of new phases during rapid solidification of the molten surface layer. In the present work, an attempt has been undertaken to improve the mechanical surface properties of titanium via precipitation of hard compound particles. The main results obtained are as follows. Ti 5Si 3, the silicide with the highest melting point (2130 °C) of all stable phases in the Si–Ti system, is formed by the transient heat treatment. During subsequent annealing for 1 h at 800 °C a fraction (14–43%) of Ti 5Si 3 transforms into TiSi. The presence of silicide precipitates in the near surface layer of titanium increases dramatically its wear resistance.

Alloying of silicon on Ti6Al4V using high intensity pulsed plasma beams

Titanium and its alloys are widely used in medical applications, for example for artificial joints, dental prosthesis on teeth. However, if these metals have to be coated with ceramic facing, some stability problems in the ceramic–titanium system arise due to the strong affinity of titanium to oxygen, which causes a reduction of the ceramic oxide. It is known that this reduction effect can be mitigated by alloying titanium or its alloys with a small amount of silicon using, e.g. an ion implantation technique. In the present work, we report the results of a new approach to alloying silicon to Ti6Al4V using high intensity pulsed plasma beams. The feasibility to form the silicide Ti5Si3 with grain size as large as 75nm is demonstrated. This silicide has the highest melting point (2130°C) of all stable phases in the Si–Ti system.

Intense plasma pulses: two modes of the use for surface processing purposes

The stainless steel substrates AISI321 were irradiated with high intensity pulsed plasma beams containing copper and nitrogen ions at various proportions. The mass change, the total copper content and elemental composition of the surface layer were examined. An effective mixing of Cu and N atoms with the substrate material accompanied by mass ablation has been revealed for N rich plasma beams. Also, an evidence of segregation effects caused by pulse melting has been found. The origin of the observed ablation effect is discussed in terms of evaporation and sputtering mechanisms.

Surface morphology of nitrogen-alloyed steels using high intensity pulsed plasma beams

Abstract Samples of single phase (AISI 321) steel and two-constituent (AISI 1045) steel were irradiated with intense nitrogen plasma pulses. The action of each pulse resulted in melting of the near surface layer and introducing the dose of about 10 17 N atoms/cm 2 . For initially smooth surfaces, in AISI 321 the main morphological changes occur after the first pulse, whereas in AISI 1045 the roughness increases with the number of pulses. For initially rough AISI 1045 (i.e. R a 0.5 μm) the pulse processing results in a decrease of R a and a significant increase (by a factor of about 2) of microhardness HV 001 . Practical conclusions are drawn from these results.