Papers by Keyword: Oxide Layer

Abstract: The ability to promote rapid osseointegration is an important criterion on the titanium implant surface. This performance is greatly determined by the roughness, wettability, and composition of the implant surface. This study aims to investigate the oxide layer formation and wettability on the EDM-titanium implant surface engineered by different micro-finishing methods (i.e. mechanical, physical, and chemical processes). The oxide layer formation was investigated by observing the wt% of oxygen formed while the wettability criterion was studied by determining the contact angle between the liquid and solid surface. The result reveals that the oxide layers formed on the sample surface, excepting Sulfuric acid (H₂SO₄) 95%-etched, show an interaction with the surface roughness and its wettability. The smoother the surface roughness of the sample, the lower the percentage of the oxide layer and the contact angle formed on the sample surface. In this aspect, the ultrasonic cleaning benchmark has the highest percentage by altering 18.84% of the oxide layer formed by the EDM process while the decrease of 75.89% generated by the H₂SO₄-etching is the lowest one. On the other hand, the higher the percentage of the oxide layer formation, the lower the wettability of the sample surface. In this aspect, the ultrasonic cleaning benchmark has the lowest wettability with a contact angle of 124º (hydrophilic) while HCl-etching is the lowest with 45º (hydrophobic). The results are notable that the ultrasonic cleaning method is able to alter wt% of the oxygen on the EDM-titanium implant surface, whereas the acid etching method can be recommended as a worthy method of the surface finishing for the semi-permanent type of implant.

Abstract: Material choices for liquid lead bismuth spallation target are some of austenitic stainless steel, ferrite martensitic steel and cold-worked austenitic stainless steel. In order to ensure materials resistance to irradiation and corrosion as well as compatibility with lead bismuth, it is appropriate to lower the incident proton current density and the process temperature, in which temperature range engineering design can control to work, especially in ADS (Accelerator-Driven nuclear transmutation System) concept. The lower limit temperature is determined from the physical melting temperature and the engineering efficiency of the steam generator involved in process control. The material related issues for liquid lead bismuth are mass loss by impinging secondary flow, wettability at the device interface for ultrasonic waves application, detachable control of the slag in the flowing system, stabilized electrical resistance between the material and the liquid lead bismuth interface. Electromagnetic fluid analyses show how flow rate relates electrical resistivity of flow channel material.

Abstract: In the present scenario aluminium is an useful metal due its admirable properties such as light weight, low cost and excellent thermal conductivity.In order to take advantages of these properties aluminium is being used to make the metal matrix composites for tribological application, In this present investigation effort has been made to assess the wear properties of Al–B₄C–Gr metal matrix composite at various temperatures such as 323° K, 373° K and 423° K. Al–B₄C–Gr Hybrid metal matrix composites were fabricated by stir casting technique. The influence of parameters like load, speed, distance and temperature on the wear rate was investigated. A plan of experiments, based on Taguchi model with L27 orthogonal array and analysis of variance was employed to investigate the influence of process parameters on the wear behaviour of these hybrid metal matrix composites. The wear resistance increased with increasing temperature, but wear resistance decreased at higher loads. It was observed that the abrasive wear is dominates while sliding as observed by SEM analysis of worn out specimens.

Abstract: In order to improve the wear resistance of H13 steel, a layer of cobalt-based cladding layer was deposited on the surface of H13 steel by plasma transfer arc welding technology. High-temperature wear test was carried out on H13 steel and cladding layer under 300N loading force, and the two materials were ground at different temperatures with 300M steel. The experimental results show that under 300N loading force, the wear resistance of the cladding layer and H13 steel decreases first and then increases with the increase of temperature, which is related to the softening and oxidation of the material. At 350°C,the material softens and the oxide layer fails to entirely cover the wear surface, so the wear resistance of the cladding layer and H13 steel is lowered. At 500°C and 650°C, the wear surface is covered by a dense oxide layer, which protects the surface of the material from direct wear. The higher the temperature is, the thicker the oxide layer is and the better the protection effect is. At various experimental temperature, the wear resistance of the cladding layer is better than that of H13 steel. The surfacing of a cobalt-based cladding layer on the surface of H13 can improve the wear resistance of H13 steel.

Abstract: This paper aims to investigate the anodising behaviour of Al-Si components produced by rheocasting, to understand the effect of the surface liquid segregation (SLS) on the anodising response. The material investigated was EN AC 42000 Al-alloy with an addition of 150 ppm Sr. The component was rheocast and conventionally liquid cast for benchmarking. The RheoMetal^TM process was used to prepare slurry and subsequently cast using a vertical pressure die casting machine. Prior to anodising, mechanical grinding was used as pre-treatment method for selected samples as comparison with components in the as-cast state. Anodising was performed on the components using a constant controlled voltage at 25 V, in 1 M H₂SO₄, at room temperature. The duration of anodising was varied from 30 mins to 120 mins to examine the relationship between oxide layer thickness and the anodising time. The oxide layer was investigated and characterised. The results demonstrated that the presence of the SLS layer, which was enriched with alloying elements, had a significant influence on the anodising behaviour of the cast component. The oxide layer thickness of the components produced by rheocasting and fully liquid casting was measured and compared. The relations between the oxide layer thickness and anodising time, as well as the casting methods are presented and discussed in this paper.

Abstract: CoCrMo alloy is widely used in the medical field to make Biomedical prosthesis,But it is difficult to process resulting in the high cost of Biomedical prosthesis, Find an efficient and low-cost processing method has become a problem to be solved. In this paper, CoCrMo alloy Biomedical prosthesis were fabricated by Electrolytic In-process Dressing grinding. We studied the ELID grinding performance, grinding force, surface quality and the formation mechanism of Corrosion-resistant oxide layer of CoCrMo alloy by using dynamometer, roughness tester, XRD and SEM. It is proposed that the ELID grinding method forms an oxide layer on the surface of the prosthesis, which increases the corrosion resistance and biocompatibility of the prosthesis so that it can be better adapt to the biological environment in vivo. It was further confirmed that the ELID grinding method is an effective method for manufacturing CoCrMo Alloy Bioprosthesis.

Abstract: Major issues related to implant failure are wear debris and metal ions release where Titanium-Aluminium-Niobium alloys still face those problems despite of better biocompatibility. Surface modification is one of the alternatives in order to reduce those wear as well as ion release problems to the host tissue. In this study, experiments were carried out to investigate the element diffusion behaviour of Ti-6Al-7Nb alloy through thermal oxidation in order to obtain coating on the surfaces for diminishing those effects. Thermal oxidation was carried out at 650°C for three different durations 6, 12 and 24 hours. It is found that at prolong time, Niobium diffusion occurs where short duration Aluminium dominates. This suggests that longer heating time promotes heavy metal diffusion by restricting diffusion of light metal and hence, dominates the heavy metal oxide layer formation. The oxide layer formed on the substrate may lead to increase the lifespan of the implant and reduces the harmful effects caused by wear debris or toxic ion from metal alloys.

Abstract: The paper contains results of studies on the formation of oxide layers on steel long-term operated at an elevated temperature. The oxide layer was studied on a surface and a cross-section at the inner surface of the tube wall. Thorough examinations of the oxide layer carried out on the inside surface of tube wall comprised:microscopic examinations of the oxide layer were performed using an Olympus GX41 optical microscope,thickness measurements of formed oxide layers,chemical composition analysis of deposits/oxides using a Joel JSM-6610LV scanning electron microscope (SEM) working with an Oxford EDS electron microprobe X-ray analyser,X-ray (XRD) measurements; the layer was subject to measurements using a Seifert 3003T/T X-ray diffractometer and the radiation originating from a tube with a cobalt anode (λ_Co=0.17902 nm). X-ray studies were performed, comprising measurements in a symmetric Bragg-Brentano geometry (XRD). XRD measurements were performed in the 15÷120° range of angles with an angular step of 0.1° and the exposure time of 4 s. To interpret the results the diffractograms were described by a Pseudo Voight curve using the Analyze software. DHN PDS and PDF4+2009 computer software and crystallographic database were used for the phase identification.

Abstract: The paper contains results of studies into the formation of oxide layers on steel long-term operated at an elevated temperature. The material studied comprised specimens of steel taken from an steam pipeline and on the flue gas side. The oxide layer adhesion tests were carried out on an automated Revetest XPress Plus instrument using a diamond Rockwell indenter. The adhesion of oxide layers, friction force, friction coefficient, scratching depth were determined as well as the force at which the layer was delaminated. It has been found that the oxide layer formed under the influence of applied pressure is more degradation in the areas where are a pores and cracks.

Abstract: The paper presents results of studies on the crystallite sizes of oxide layer formed during a long-term operation on steel operated for a long time at an elevated temperature. This value was determined by a method based on analysis of the diffraction line profile, according to a Scherrer formula. X-ray studies were carried out on the inner surface of a tube (in a flowing medium environment), then the layer’s surface was polished and the diffraction measurements repeated to reveal differences in the originated oxides layer. X-ray phase analysis was performed using a SEIFFERT 3003 T/T X-ray diffractometer, with a cobalt tube of λ_Co = 0.17902 nm wavelength. XRD measurements were performed in the 15÷120° range of angles with an angular step of 0.1° and the exposure time of 4 s. To interpret the results (to determine the 2θ position and the total intensity I_Net) the diffractograms were described by a Pseudo Voight curve using the Analyze software. A computer software and the PDF4+2009, DHN PDS crystallographic database were used for the phase identification.