Influence Of Nitrogen Flow Rate In Reducing Tin Microdroplets On Biomedical TI-13ZR-13NB Alloy

Cathodic arc physical vapor deposition (CAPVD) is one of the promising techniques that have a potential to coat titanium nitride (TiN) on biomedical implants due to its good adhesion and high evaporation rate. However, this method emits microdroplets which have the possible detrimental effect on the coating performance. Past studies indicated that micro droplets can be controlled through proper deposition parameters. In the present work, an attempt was made to study the effect of nitrogen gas flow rates (100 to 300 sccm) on TiN coating of the Ti-13Zr-13Nb biomedical alloy. Scanning electron microscopy (SEM) was used to evaluate surface morphology and coating thickness while crystal phase of the coated substrates was determined using X-Ray Diffraction (XRD). Image analysis software was employed to quantify microdroplets counts. Results show that higher nitrogen gas flow rate able to decrease a significant amount of microdroplets and concurrently increase the thickness of TiN coating. A mixed crystal planes of (111) and (220) are obtained on the coated substrates at this setting which exhibits denser structure with higher adhesion strength as compared to substrates coated at the lower N2 gas flow rate

Fatigue analysis of cannulated pedicle screw

A cannulated pedicle screw (CPS) is a typical type of bone screw used to implant into a vertebral in the medical field. The purpose of these screws is to treat lumbar (lumbosacral) spine trauma. The screw is used to form spinal fusion transpedicle screw devices. Although the CPS is made by high strength material, the fatigue failure is still happened by time. Nevertheless the detail investigation on fatigue life cycle of screw also is lacking. This is maybe due to difficulty to investigate it by experimental (in vivo) since it is involved with human life. However, this paper focus on investigation of CPS fatigue life cycle using finite element method (FEM) since it is considered as acceptable method for biomechanics. By using the Ansys software as finite element method software, we can properly estimate the life span of the CPS. Based on the FE simulation results obtained, we found that our FE model is capable to predict fatigue life of CPS since the FE von mises stress result of our model only 7.1% difference with previous research result. Based on the prediction by FEM, the CPS life cycle is up to 3.1 years if the continuous load 11000 N is applied on the CPS by the time. Although our FE model is proven has potential in assisting CPS design, however in the future fabrication of the CPS and further testing needs to be conducted in order to evaluate this finding experimentally

Prediction of Malaysian Talus Bone Morphology Using Artificial Intelligence

Book cover pp 29–37Cite as Part of the Abstract Talus fractures keep on presenting to a difficult and generally experienced gathering of injuries. This published report shows that not all the current bone implants are the ideal counterpart for the specific population. Along these lines, this investigation received a three-dimensional (3D) estimation way to deal with given exact information to the anatomical morphology of talus bone. Seventy-four Malaysian healthy subjects experienced computerized tomography (CT) arthrography. 3D computerized talar models were generated and three morphological boundaries predicted through Mimics and Solidworks software. Sagittal Talar radius (STRa), Throchlea Tali length (TTL), Talar Anterior width (TaAW) are the most part chosen. Information investigation was directed by determination of information test through Matlab programming. In this way, the information was obtained dependent on the artificial intelligence (AI) forecast of the talus bone morphometric. While, the AI strategy demonstrated a more noteworthy limit of forecast in regards to the low level of mistake and high correlative qualities since the average percentage errors of the predicted talus bone morphology parameters are around 10% which 11.3% for STRa, 12.95% for TaAW, and 9.45% for TTL. AI is an exceptionally exact prescient technique and can be utilized as helping instruments in developing bone implant specifically for Malaysian patient and for Asian patient in general

Deformation Behaviour of a High Carbon Co–Cr–Mo Medium-Entropy Alloy via Thermal Oxidation

Thermal oxidation is widely used in substrate surface modification before applying bioceramic coating to enhance implant resistant against corrosion and biocompatibility. In this work, mechanical and microstructural characteristics of a medium-entropy alloy Co61.9Cr29.6Mo6.5C0.24 (in wt.%) was thermally oxidize under controlled furnace atmosphere, at 450 °C, 650 °C, 850 °C, 1050 °C and 1250 °C for 3 h. It has been demonstrated that by oxidizing high carbon Co–Cr–Mo alloy can create a reasonably thick, stable and hard Cr2O3 layer on the substrate at 1050 °C. The exchange of substrate colour from silver to brownish and lastly dark green of oxide layer was observed and is evident from the variations of the surface morphology which is also a cause response to the increment of temperature. Within the interval of extremely high temperature considered (1250 °C), the alloy exhibits several unusual features, such as presence of massive porosity with clumpy blended of distinct composition of oxide layer like CoCr2O4 and Co0.8Cr0.2. The results also demonstrate that Cr2O3 layer recede in thickness as the temperature reaches 1250 °C and experienced oxide layer spalling due to bounteous chemosorption of O2 atoms react with dominant elements like cobalt and chromium in the substrate

Effect of thread profile variation on pullout and bending strength of a pedicle screw

Pedicle screw is an important instrument in treatment of spinal degeneration or disease. However, the pedicle screw failure still occurs due to the screw loosening, fracture and pullout. There are few factors that affected the pedicle screw performance as reported by previous research but still lacking study related to the pedicle screw thread profile. Thus, the aim of this research is to investigate the effect of variation of thread pitch on the pullout and bending strength of pedicle screw. The research is carried out by constructing 3D pedicle screw models (model 1-6), importing the models into ANSYS, meshing and post processing analysis. The equivalent or Von-Mises stress used to compare the bending and pullout performance of the pedicle screws. Based on the obtained finite element analysis result, the single thread pedicle screw (model 3) has the optimum performance in bending while the model 4 is the optimum in pullout performance. While, for the dual threaded pedicle screw, the model 6 which has coarse thread pitch at screw tip is better than model 5 (fine thread). Thus, it can be conclude that both the single and dual threaded pedicle screw with coarse thread pitch has lower maximum equivalent stress than fine thread pitch, which is means it has better bending and pullout performance

The Effect of PLA/HA Coating Thickness on Crack Formation and Corrosion Performance

Surface modification of metallic implants is often required to facilitate positive interaction between the implant and the surrounding hard tissue. In this study, a polymer-ceramic composite coating of polylactic acid/hydroxyapatite (PLA/HA) was successfully deposited on a Co–Cr–Mo alloy by the dip coating method in chloroform suspension at room temperature. The effect of various PLA/HA dipping layers was studied and the dip coating process parameters were optimized in order to obtain a homogeneous, crack free, densely packed and adhesive coating. It is found that PLA/HA-coated substrate with 3 dipping layers were denser and less crack sensitive compared to 6 dipping layers. Although it is hypothesized that a coarser coated surface helps to facilitate ingrowth of osseous tissue in human body, but current findings show opposite manners due to the fact that a higher corrosion rate was obtained. The coated substrate with 6 dipping layers also were found more profound to micro-cracks and delamination with a lower microhardness value compared to coated substrate with 3 dipping layers

Analysis and simulation of temperature distribution and stress development in wire EDM of Tungsten carbide

The main objectives of this research are to investigate the performance of temperature distribution and equivalent Von- Mises stress development on tungsten carbide, determine the effect of different machining parameters on the tungsten carbide workpiece, prepare a set of parameters, temperature distribution and stress development that can be compared with the experimental result and to optimize the machining parameters for machining tungsten carbide using wire EDM. However, wire EDM is a complicated stochastic nature process mechanism and it has a very large number of parameters that should be considered. It is quite hard to select the best set of parameters in experimenting. In this research, the Ansys software was used to simulate the maximum temperature and maximum equivalent (Von-Mises) stress result of machining the tungsten carbide by wire EDM. The input parameters selected in conducting the simulation are pulse- on time and servo voltage. The wire diameter, convective coefficient, thermal expansion coefficient, current, thickness of the workpiece and wire material is taken as fixed parameters. By using Taguchi’s L9 orthogonal array, the optimal value is obtained for maximum temperature and maximum equivalent (Von-Mises) stress. Additionally, the analysis of variance (ANOVA) is a useful technique to identify the most important factor that affecting the output response

Elemental Diffusion Behaviour of Biomedical Grade Titanium Alloy through Thermal Oxidation

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

Improvement of corrosion resistance of tin coated on titanium alloy for biomedical application

This work aims to study the effect of mechanical treatment technique on titanium coated with PVD for the enhancement of corrosion resistance for the biomedical implant. First, substrates were coated with TiN via PVD then applied the mechanical treatment through ultrasonic vibration. Results show that all coated samples treated with ultrasonic vibration improve the surface of the coated sample and produce a compact coating as compared with a substrate coated without mechanical treatment. The corrosion test evaluated by Potentiodynamic polarization and Electrochemical Impedance Spectroscopy indicated that all coated samples treated with mechanical treatment showed high corrosion resistance as compared with the untreated sample. It can be concluded that mechanical treatment which is a simple technic can be used as an alternative to improve the corrosion resistance thus reduce the implant and manufacturing cost for biomedical applications

Performance enhancement of energy saving and machining characteristic in electrical discharge machining on magnesium alloy: A review

Magnesium alloys have been widely used in biodegradable applications due to it tends to corrode inside the human body and combined with its initial mechanical property. Current research revealed that the structural stability of the implant is disturbed and lost rapidly due to the increased rate of degradation of magnesium inside the human body. Because of that, non-traditional machining method such as electrical discharge machining (EDM) die sinking process is implemented to create an intricate form with a high tolerance of magnesium alloy. The advantages of EDM are that it allows a versatile adaption of implant behaviour in machining complex 3D structures along with high corrosion resistant properties of electrochemical surface treatment. Various material types with different parameters are investigated to determine the influence of input process parameters on the energy saving, and machining characteristics included surface roughness, material removal rate, and tool wear rate. In addition to improving the machining performance especially in energy-saving, input on the machining parameter needs to be considered due to interaction with added conductive particles which would affect the size of discharge energy. The objective of this paper is to summarize the findings in research of EDM’s energy-saving and machining characteristics on magnesium alloy and to explore challenging issues that need to be resolved for future references and recommendations