Mingren Sun

The vibratory stress relief of a marine shafting of 35# bar steel

Abstract The marine shafting is made from a 35 # bar steel. The 35 # bar steel is named based on PR China national standard GB 699-88, “Quality carbon structure steel technical requirements,” the 35 # bar steel corresponds to 060A35, B.S. The bar steel was hot rolled, piled and air cooled; hot rolling, cooling and microstructure transformation formed macro residual stress in the bar steel. There is high macro residual stress in the 35 # (060A35, B.S.) bar steel. Worker shaped the bar steel into marine shafting with lathe. During machining, the macro residual stress releases and thus causes considerable deformation of the marine shafting. The vibratory stress relief is introduced to the bar steel that was shaped into marine shafting. The vibratory stress relief of the bar steel of the marine shafting was carried out. The tensile properties of the bar steel were measured before and after vibration. While the bar steel was vibrating, six different location axial surface vibratory stresses were measured with dynamic strain gauge; the axial surface vibratory stresses distributive curve is obtained. The macro residual stress was measured with X-ray stressmeter before and after vibration. The macro residual stress decreased notably by about 48%. The tensile properties changed slightly. The vibratory wave is a standing wave. The vibratory stress relief is valid for macro residual stress relieving of the bar steel of the marine shafting. The mechanism of the macro residual stress relieving by vibration on the bar steel of marine shafting is discussed. The “double-dynamic mechanism” is introduced to explain the course of macro residual stress relieving in the test.

Structure and frictional characteristics of Ti–6Al–4V plasma-based ion implanted with nitrogen then acetylene

Abstract The concentration depth profiles, structure and ball-on-disk frictional characteristics of Ti–6Al–4V plasma-based ion implanted with nitrogen (energy 60 keV) then acetylene (energy 10–30 keV) were investigated. The implanted samples ( R =0.05–2×10 11 Ω cm −1 for the modified layers) included three zones: a top H–DLC zone, a C, N, Ti, O coexisting intermediate zone which had undergone chemical state changes indicating TiN, TiC, and Ti(C,N) second phases were formed, and the bottom zone of the substrate. The samples showed higher hardness especially at low plastic penetrations and higher wear resistance (lower coating brittleness) in the order of 10, 20, 30 and 10, 30, 20 keV implantation, respectively. A tribofilm transferred from disc to ball wear surface was found, lowering friction coefficient and reducing the ball wear, and this result possibly caused the ball weight increase after wear testing. With decreased load and increased speed, the function of the transfer film became more important, and tribological properties were improved (stable friction coefficient 0.15–0.25). When counterbody AISI 52100 was changed to Ti–6Al–4V modified as the disc, initial friction and wear life decreased, and wear was changed from only disc to both disc and ball abrasive dominated. The as-implanted samples demonstrated greatly improved tribological properties compared with unimplanted ones, showing a possible optimal implantation energy.

Metal plasma source ion implantation using a UBM cathode

Abstract A brief description is given of an industrial prototype DLZ-01 PSII implanter which uses a radio frequency source for enhancing plasma production and four unbalanced magnetron (UBM) cathodes for metal particle achievement. The emphasis of this description is put on the structural traits of UBM cathodes and the metal plasma properties. The characteristics of this method are also discussed. For preliminary research, the same UBM deposition and fixed implantation parameters are selected. The characteristics of the UBM cathodes are described using the unbalanced magnetic field distribution. The ionization determined by the detection of the deposition rate and saturation current is very small (

Composition and corrosion resistance of cerium conversion films on 2195Al-Li alloy

Abstract The Ce conversion films on 2195Al-Li alloy without and with post-treatment were studied and the corrosion resistance was evaluated as well. The surface morphology was observed by scanning electron microscopy (SEM), and the chemical composition was characterized by X-ray photoelectron spectroscopy (XPS). The corrosion behaviors of 2195Al-Li alloy and conversion coating were assessed by means of potentiodynamic polarization curves. The experimental results indicated that after post-treatment the surface quality was improved significantly. According to XPS, the conversion coating after post-treatment was mainly composed of CeO 2 , Ce 2 O 3 , Ce-OH and a little MoO 3 and MoO 2 . The results of potentiodynamic polarization curves revealed that the conversion coating with post-treatment possessed better corrosion resistance than bare alloy and Ce conversion coating without post-treatment.

Tribological behaviour of duplex treated Ti–6Al–4V: combining nitrogen PSII with a DLC coating

Abstract The chemical structure and tribological behaviour of Ti–6Al–4V plasma source ion implanted with nitrogen then DLC-coated in an acetylene plus hydrogen-glow discharge (bias voltage −10 to −30 kV) were investigated. The as-modified samples have a TiN/H:DLC multilayer architecture (coating resistivity 1.6×10 9 to 2.4×10 11 Ω/cm) and exhibit higher hardness, especially at low loads or plastic penetrations in the order of deposition bias voltage −10, −20 and −30 kV. At a lower contact load (1 N) and higher sliding speed (0.05 m/s), frictional properties in most cases improved, as did wear properties. At a higher contact load (5 N) and lower sliding speed (0.04 m/s), friction showed almost no improvement, and wear properties deteriorated. When the material of the counterbody was then changed from AISI 52100 to Ti–6Al–4V modified as the disc (contact load 5 N unchanged, sliding speed decreased), the friction coefficient decreased (but showed no improvement compared with the unmodified sample), while wear properties deteriorated further, and wear was changed from just the disc to both disc and ball, abrasive and adhesive dominated. Transfer films, mainly made up of wear debris transferred from the disc wear surfaces, were formed on the wear scars of the counterbodies. The deterioration of wear properties of the modified samples at the higher contact load is considered to be caused by the “thin ice” effect.

Preparation of Ti/N and Ag/TiNx Multilayers by Plasma Based Ion Implantation With Multi-Targets Unbalanced Magnetron Sputtering

Ti/N and Ag/TiNx multilayers were prepared by plasma based ion implantation (PBII) with multi-targets unbalanced magnetron sputtering and analyzed by Auger electron microscopy (AES) and X-ray photoelectron spectroscopy (XPS). Nitrogen plasma gas and Ti and Ag multi-targets were used in this study. It was found that both gases and metal elements could be implanted into the samples. Ti/N and Ag/TiNx multilayers were successfully fabricated by multi-cycle PBII with nitrogen plasma gas and Ti and Ag unbalanced magnetron sputtering. The possibility of design and fabrication of multilayers by this technique is also discussed. This technique for the deposition of films may find more applications.

Tribological behavior of TiC/DLC multilayers prepared on Ti–6Al–4V alloy by plasma-based ion implantation

Plasma-based ion implantation (PBII) of carbon (time 1–3 h) and subsequent glow discharge deposition of carbon produced TiC/DLC multilayers on Ti–6Al–4V samples (TiC second phase formed in the near surface region plus DLC surface layers). The as-modified samples showed higher hardness than the uncoated sample especially at low plastic penetrations in the order of the 1, 2, and 3 h carbon implantation, but had brittle wear appearances. When the implantation time was increased, the brittleness increased, hence the tribological properties in most cases deteriorated. A tribofilm transferred from a disk wear surface was formed on the wear surface of a counterbody made of bearing steel AISI 52100, lowering the friction coefficient, and reducing the ball wear. When the wear load was decreased and sliding speed increased, the function of the tribofilm became more important; the friction decreased, and the wear properties improved, with a stable friction coefficient ranging from 0.1 to 0.2. But when the counterbod...

Nanoscratch behaviors of La0.7Sr0.3MnO3+δ thin films

Abstract The nanoscratch behaviors of La 0.7 Sr 0.3 MnO 3+δ films, which were deposited with ratio of O 2 /(O 2 +Ar), ranging from 4.4% to 45.6%, by DC magnetron sputter, were investigated by a nanoindentation technique. The results indicated that the friction coefficient between the films and the diamond tip depended on the loading critical load. The friction coefficient was about 0.08–0.12 when the loading normal load was less than the loading critical load. The films displayed excellent elastic recovery after unloading. When the loading load was larger than the loading critical load, plastic deformation and ploughing appeared for the films. The friction coefficient was about 0.43 when the film was damaged completely. The suitable decrease in ratio of O 2 /(O 2 +Ar) could improve the nanoscratch resistance of the films. The film deposited with O 2 /(O 2 +Ar)=25% possessed better scratch resistance due to good elastic recovery, high nanohardness, and critical load. The loading critical load of the film was larger than 80 mN.

XPS Study on Chemical State and Phase Structure of PBII Nitriding M50 Steel

X-ray diffraction (XRD) and X-ray photoelectron spectroscopy were used to study the structure and the element chemical states of plasma-based ion implantation (PBII) nitriding M50 steel. An ~70-nm-thick oxygen-rich layer was formed in the surface after PBII treatment, where C and V elements were absent, Cr and Mo elements were in the manner of oxide, and Fe element was in the manner of Fe₃O₄ and iron nitride. XRD patterns revealed that the Fe₁₆N₂ phase was formed in the subsurface of the nitrided layer. Four different chemical states of nitrogen with binding energies of 404.1, 399.2, 396.7, and 394.3 eV were found in sequence with sputtering time increasing, which were confirmed to belong to NO bonding, Fe₃(N, O) [or Fe₄(NO)], Fe₃N (or Fe₄N), and Fe₁₆N₂.