Thin Layer Activation Research Articles

Thin layer activation-based evaluation of tribological behaviour of light ion-implanted metallic samples

In our Cyclotron Laboratory wear and/or corrosion studies of metallic machine parts are performed on a routine basis by using the Charged Particle Surface Activation method, also commonly known as the Thin Layer Activation (TLA) technique. In principle, this method consists of an ion beam irradiation of the surface of interest (typically using proton and deuteron beams), followed by in-situ radioactivity monitoring, on a testing bench or in normal running conditions. The observed changes in radioactivity are then transformed in mass losses, by using a specific calibration procedure. In spite of the high reliability of the method, which allows fast and accurate determinations under real operating conditions, the issue of possible influence of ion bombardment upon the tribologic properties of irradiated components had yet to be clarified. To do that, a dedicated set-up was designed so as to ensure a simultaneous irradiation of the disk-shaped samples at various incident beam energies and doses. Since the expected structural modifications were associated not only to ion-induced damages, but also to the local heating, we tried to outline the contribution of each of the two above-mentioned effects. Consequently, the microstructure effects have been investigated by both electronic and metallography microscopy. The Vickers micro-hardness test has been taken before and after irradiation of each sample. Two main outcomes can be reported: the use of radioactive labelling for wear and corrosion control using MeV beams with doses below 10 17 ions/cm 2 of light particles such as protons and deuterons does not lead to significant changes of the tribologic properties of the studied machine part; and besides, wear diagrams (wear levels vs. running time) for Carbon Steel Alloy (OL-45 in Romanian standard, 0.45% carbon) and Cu 63 Zn 37 brass irradiated at different doses (10 17 – 10 18 ions/cm 2) have been obtained.

Excitation functions of deuteron induced nuclear reactions on natTi up to 20 MeV for monitoring deuteron beams

Excitation functions were measured for nuclear reaction on natural Ti leading to the formation of the 43,44m,44g,46,47,48Sc and 48V isotopes up to 21 MeV deuteron energy using the stacked-foil technique. The measured excitation functions, the calculated thick target yield and activity calibration functions for the thin layer activation technique have been compared with the earlier literature data. The investigation with respect to their potential application as monitor reactions showed that the reactions on natTi could be recommended for monitoring deuteron beams, especially the natTi(d,x) 48V reaction, in the energy range from 3 up to 20 MeV. However, to clear up the discreancies in the literature and to compare the results with other monitor reactions, additional measurements are required.

Ultra thin layer activation by recoil implantation of radioactive heavy ions: applicability in wear and corrosion studies

A new calibration procedure is proposed for the application of recoil implantation of radioactive heavy ions (energies between a few hundred keV and a few MeV) into the near surface of materials as part of a research programme on submicrometric wear or corrosion phenomena. The depth profile of implanted radioelements is performed by using ultra thin deposited films obtained by cathode sputtering under argon plasma. Two curves for 56Co ion in nickel have been determined for implantation depths of 110 and 200 nm, respectively, and stress the feasibility and reproductibility of this method for such activated depths. The achieved surface loss detection sensitivities are about 1 and 2 nm respectively. The on line detection mode is performed directly on the sample of interest. A general description of the method is presented. A study of the reaction kinematics followed by a general treatment on the irradiation parameters to be adopted are also developed with the intention of using the ultra thin layer activation method (UTLA) to further applications in research and industry.

Resistance-to-wear testing of metallic machine components by charged particle surface activation

Surface activation, commonly known as Thin Layer Activation (TLA), is an ion beam technique generally employed for wear and/or corrosion monitoring in industrial plants, especially related to applications in engine and machine construction industries. For an efficient industrial application of this technique, one must foresee some specific irradiation set-ups as well as the measuring method, having in mind the diversity of machine components which might be subjects of such studies and the tribological phenomena involved. Some of these aspects are mentioned the paper. In principle, the TLA-based measuring methods exploit the correlation between the loss of material owing to wear and the resulting changes in radioactivity. Two such measuring methods are derived; they will be reviewed briefly in the paper and illustrated by wear diagrams obtained for several parts of running machines such as piston-rings, linear cylinders and bearing crankshafts, together with a study of characteristics of different (unspecified) lubricant oils. An example where a TLA-based method has been successfully applied, for material couple characterisation on Timken testing stands, is also presented. The paper ends with a typical remnant measuring method application executed for the Romanian Railway Company.

Thin layer activation for measuring fretting wear and material transfer in iron alloys

An important difference between fretting wear and macroscopic wear processes lies in the amounts of wear volume. Because of the small relative displacements in fretting wear the wear volumes are much smaller than in (classical) macroscopic wear processes. Classical wear measuring techniques such as weighing and 2D-profilometry often fail to determine the fretting wear volumes. Their sensitivity as well as their accuracy are inadequate. 3D-profilometry partially solves this problem but the obtained wear results do not take eventual material transfer between the test specimens into account. In this work thin layer activation (TLA) is presented as a potentially powerful tool for quantitative fretting studies, especially in relation to material transfer. In contrast with the other mentioned wear measuring technique TLA allows measurements of very small amounts of wear as well as material transfer between the test specimens. Preliminary results are reported for steel specimens. A surface zone of 7 mm 2 of one test specimen, in which the wearing zone during the fretting experiment is situated, is irradiated with protons from a cyclotron. As a result of a nuclear reaction the iron in the irradiated test specimen forms radionuclides, mainly cobalt-56, in a surface layer of 260 μm depth. The amount of cobalt-56 as compared to iron is negligible so that the physical and chemical properties of the irradiated zone remain unaffected. Measuring the gamma rays of cobalt-56 in the wear debris gives quantitative information about the wear volume and measuring the mating surface gives information on the transfer volume.

Ion beam-based studies for tribological phenomena

Custom-designed experiments based on the Thin Layer Activation technique (TLA) were completed, providing information on the wear level of some engine components with additional data on transfer and adhesion of material between metallic friction couples using the RBS method. RBS experimental results concerning material transfer for a steel-brass friction couple are presented and discussed in the paper. Also, the types and concentrations of the wear products in used lubricant oils were determined by in-air PIXE. A sequential lubricant filtering-based procedure for determining the dimension distribution of the resulting radioactive wear particles by low level γ-spectrometry is presented. Experimental XRF spectra showing the non-homogeneous distribution of the retained waste particles on the filtering paper are shown.

Cyclotron accelerated beams applied in wear and corrosion studies

Wear and corrosion processes are characterized by a loss of material that is, for machine parts and components, usually in a micrometer's range. That is why, in the last two decades, many direct applications in machine construction, petrochemical and metallurgical industries based on the Thin Layer Activation (TLA) technique have been developed. In this paper general working patterns together with a few examples of TLA applications carried out using our laboratory's U-120 Cyclotron are presented. The relation between the counting rate of the radiation originating from the component's irradiated zone and the loss of the worn material can be determined mainly by two methods: the oil circulation method and the remnant radioactivity measuring method. The first method is illustrated with some typical examples such as the optimization of the running-in program of a diesel engine and anti-wear features certifying of lubricant oils. There is also presented an example where the second method mentioned above has been applied to corrosion rate determinations for different kinds of unoxidable steels used in inert gas generator construction.

Metrology conditions for thin layer activation in wear and corrosion studies

Thin Layer Activation (TLA) is an ion beam technique. This method consists of an accelerated ion bombardment of the surface of interest of a machine part subjected to wear. Radioactive tracers are created by nuclear reactions in a well defined volume of material. Loss of material owing to wear, corrosion or abrasion phenomena is characterized by monitoring the resulting changes in radioactivity. For the industrial application of this method, special attention has been paid during irradiation to the range of activated thickness, yields and activation homogeneity and to on-line radioactivity measurements. There are two basic methods for measuring the material loss by TLA technique. One of them is based on remanant radioactivity measurements using a previously obtained calibration curve. The second is based on measuring the increasing radioactivity in the lubricant due to suspended wear particles. In this paper, we have chosen to present some calibration curves for both proton and deuteron irradiation of Fe, Cr, Cu, Ti and Ni samples. Thickness ranges are indicated and intrinsic error checking and calculational procedures are also presented. The article ends with a review of some typical experiments involving running-in programme optimization and lubricants certifying procedures.

薄層放射化法の産業への利用

薄層放射化法の産業への利用

Investigation of the charged particle nuclear reactions on natural boron for the purposes of the thin layer activation (TLA)

Boron of natural composition was investigated in the form of NiBSi metallic-glass foil to determine the cross-section functions of the natB(p,x) 7Be and the natB(d,x) 7Be nuclear reactions. These reactions are very important from the point of view of Thin Layer Activation (TLA) technique to monitor the wear of boron-containing superhard materials (e.g. BN), because the 7Be with its half-life of 53 d and gamma-energy of 447 keV is very suitable for wear measurements. The possibility of recoil-implantation of the radioactive nuclei was also studied.

Determination of cross section of α-induced nuclear reaction on natural Cr and Zr by stacked foil activation for thin layer activation analysis

The cross sections of different α-induced nuclear reactions on natural chromium and zirconium have been determined at different energies of the α-particles by the stacked foil activation technique using the 40 MeV α-beam from Variable Energy Cyclotron at Calcutta. The reaction channels studied from the stable isotopes of natural Cr and Zr are (α, xn), (α, p), (α, p xn) and (α, αn) (where x = 1 and 2). The excitation functions have also been reported for the energy range from 10 to 40 MeV of α-particles. The experimentally determined cross sections have been compared with the theoretical values computed on the basis of the hybrid model using a program ALICE 85/300. The analytical validation of the experimental values has been carried out with a vanadium target for which cross sections are already reported in the literature. The purpose of generating of the above cross sections is to support the thin layer activation technique for the study of surface wear in Cr and Zr based metals/alloys.

A nuclear method to measure spallation by thermal cycling of protective surface layers

After a general introduction on spallation by thermal cycling, the principle of Thin Layer Activation (TLA) is outlined. A practical setup to measure spallation of protective surface layers by thermal cycling using TLA is discussed. Its use is illustrated with the study of the spallation behaviour of an advanced thermal barrier coating. It is shown that among the various benefits, TLA has a direct relation to material loss and shows a significant increase in sensitivity over other test methods. Due to its intrinsic properties, TLA can contribute to a greater scientific understanding of material degradation by thermal cycling and it can provide a more reliable assessment of the service lives of technical components.

Study of the flaking‐off phenomenon on a jet Engine's shaft bearing using the thin layer activation technique

AbstractThe Thin Layer Activation technique has been applied in order to study the flake‐off phenomenon on a jet engine's shaft bearing. The external track of the bearing has been activated following the reaction 56Fe(p,n)56Co, over a depth of 80 μm. In spite of a very low activation level, the first signs of flaking‐off were detected 30 min before any significant increase in the vibration level appeared. At that point, the mass of particles leaving the track was measured on line, with a precision of 0.2 mg.

イオンビーム利用の基礎と現状 Ｖ．イオンビームの応用 ３．工業利用 ３．７薄層放射化法による摩耗計測

イオンビーム利用の基礎と現状 Ｖ．イオンビームの応用 ３．工業利用 ３．７薄層放射化法による摩耗計測

Study of wear of combustion engines by means of thin layer activation using accelerated charged particles

The improvement of running-in programs for internal combustion engines by using the thin layer activation technique is presented. The wear was measured as function of time, simultaneously for cylinder walls and piston rings.

Measurement methods for determination of spallation of oxide scales

Several experimental techniques are being used to obtain numerical information concerning the spallation of protective oxide scales formed during high temperature corrosion. These data are required both for mechanistic modelling of the spallation process and for the construction of spall databases for engineering design purposes. By far the most universally employed experimental method is gravimetry, involving either continuous or discontinuous measurements. Thin layer activation can monitor spallation and has potential for further exploitation. Acoustic emission and, to a lesser extent, the resonant frequency technique are the principal methods used to detect or monitor cracking which precedes spallation. These experimental procedures are described and assessed, while further technique development requirements are detailed.

Thin layer activation techniques at the U-120 cyclotron of Bucharest

The Thin Layer Activation (TLA) technique is a nuclear method especially used for different types of wear (or corrosion) investigations. Experimental results for selection criteria of nuclear reactions for various tribological studies, using the IPNE U-120 classical variable energy Cyclotron are presented. Measuring methods for the main types of wear phenomena and home made instrumentations dedicated for TLA industrial applications are also reported. Some typical TLA tribological applications, a nuclear scanning method to obtain wear profile of piston-rings are presented as well.

MeV ion processing applications for industry

Ions beams with MeV energies produce a variety of interactions with matter, broadly classified as either electronic or nuclear. These interactions in turn lead to changes in the properties of the matter which may be beneficial or detrimental. In high technology industry, use is increasingly made of ion beam technologies to process novel materials. Typical applications include high energy implantation, in which the deposition of a specific element at depth within the structure of material is the required objective, and irradiation modification, in which the balance between the beneficial and the detrimental effects of the fast ion interactions is exploited. The basic principles behind MeV ion processing are described. Broad areas of application in industrial materials include effects in ion beam analysis, Thin Layer Activation for wear and corrosion measurement, carrier lifetime control in electronic devices, and the simulation of radiation damage effects in, for example, solar cells for spacecraft. New development areas are described in which subtle but potentially significant changes in the chemistry of surfaces and interfaces may be generated by exposure to MeV ion beams.

Production of 51Cr by deuteron activation of natural chromium

The investigation of the nuclear activation yield of natural chromium was dictated by the technological interest of the use of the thin layer activation technique for the study of surface performances of chromium based materials. For practical applications, 51Cr has been selected as tracing element. Three deuteron induced reactions lead to 51Cr in the energy range from 0 to 18 MeV: 50Cr(d, p) 51Cr, 52Cr(d, p2n) 51Cr and 50Cr(d, n) 51Mn → 51Cr). The activation yield for the deuteron induced production of 51Cr as a function of the energy has been measured experimentally via the stacked-foil method using an energy variable cyclotron. To compute the energy incident on each foil and its distribution due to multiscattering effects, a Monte Carlo program has been elaborated, simulating the energy straggling of a particle beam passing through a stacked foil sample of given thickness and composition. The yield profile has also been calculated using two computer codes, STAPRE and ALICE.

Wear measurement of the cutting edge of superhard turning tools using TLA technique

Wear measurement on superhard boron nitride and artificial diamond turning tools was performed using thin layer activation (TLA) technique. The samples were irradiated in two different geometries to improve the sensitivity of the method and change the region of wear to be investigated. The most proper irradiation parameters and nuclear reactions were investigated for both kind of tools.