Dewan Muhammad Nuruzzaman

The Experimental Characteristics and Evaluation of Nylon-12 in Erosion Process

Polymer materials are used in a wide range of applications. The erosion properties of nylon-12 were analyzed in this study. Randomly-shaped sand (SiO2) particles of various sizes (300–355 lm, 355–500 lm, and 500–600 lm) were selected as erosive elements. Impingement angles between 15 and 90_, impingement velocities between 30 and 50 m/s, and stand-off distances 15–25mm at ambient temperature were tested. During testing, the maximum erosion of the tested polymer composite occurred at 30_ angle of impingement, indicating a ductile nature of the test material. Erosion increased with impact velocity and decreased with stand-off distance. The erosion rate varies from approximately 5 to 1600 mg/kg at different combinations of impact velocity, impact angle, and other related parameters. The mean S/N ratio was found to be _41.35 dB, which reflects the average erosion rate under different test conditions. Test results were evaluated using Taguchi’s concept to minimize the observations needed, and analysis of variance (ANOVA) was used to identify interactions between tested parameters and identify the most significant parameters. Surface damage was examined using scanning electronic microscopy (SEM) to examine the nature of the wear behavior. The morphology of tested material showed micro cutting, micro cracking, ploughing, and deformation as dominating damage characteristics of impacting surfaces.

Three-Dimensional Finite Element Modeling of Thermomechanical Problems in Functionally Graded Hydroxyapatite/Titanium Plate

The composition of hydroxyapatite (HA) as the ceramic phase and titanium (Ti) as the metallic phase in HA/Ti functionally graded materials (FGMs) shows an excellent combination of high biocompatibility and high mechanical properties in a structure. Because the gradation of these properties is one of the factors that affects the response of the functionally graded (FG) plates, this paper is presented to show the domination of the grading parameter on the displacement and stress distribution of the plates. A three-dimensional (3D) thermomechanical model of a 20-node brick quadratic element is used in the simulation of the thermoelastic behaviors of HA/Ti FG plates subjected to constant and functional thermal, mechanical, and thermomechanical loadings. The convergence properties of the present results are examined thoroughly in order to assess the accuracy of the theory applied and to compare them with the established research results. Instead of the grading parameter, this study reveals that the loading field distribution can be another factor that reflects the thermoelastic properties of the HA/Ti FG plates. The FG structure is found to be able to withstand the thermal stresses while preserving the high toughness properties and thus shows its ability to operate at high temperature.

Experimental analysis of aluminum alloy under solid particle erosion process

The erosion behaviors of aluminum alloy have been evaluated practically at different test conditions under ambient temperature. Irregular silica sand (SiO2) is used as an erodent within the range of 300–600 µm. The impact velocity within 30–50 m/s, impact angle 15–90°, and stand-off distance 15–25 mm considered as related parameters. The maximum level of erosion is obtained at impact angle 15° which indicates the ductile manner of the tested alloy. The higher the impact velocity, the higher the erosion rate as almost linear fashion is observed. Mass loss of aluminum alloy reduces with the increase of stand-off distance. A dimensional analysis, erosion efficiency (η) and relationship between friction and erosion indicate the prominent correlation. The test results are designated using Taguchi’s concept to ensure the minimization of observations for clarification of results in alternative process. ANOVA data analysis is considered to signify the interaction of tested parameters as well as identifying most influencing operating parameter. S/N ratio indicates that there are 2.92% deviations estimated between predicted and experimental results. To elaborately analyze the results, GMDH method is mentioned. After erosion process of the tested composite, the damage propagation on the surfaces is examined using SEM for confirming wear mechanisms. The elemental composition of eroded test samples at varying percentage of aluminum is analyzed by energy dispersive X-ray spectroscopy analysis.

Erosive wear characteristics of multi-fiber reinforced polyester under different operating conditions

Composite materials are used in a wide range of applications. The erosion properties of combination of glass, jute and carbon fiber-reinforced polyester were analyzed in this study. Randomly-shaped silica (SiO2) particles of various sizes (300-355μm, 355-500μm, and 500- 600μm) were selected as the erosive element. Impingement angles between 15-90°, impingement velocities between 30-50 m/sec, and stand-off distances of 15-25 mm at ambient temperature were selected. During experiment, the maximum erosion of the tested composite occurred at 60° impingement angle, indicating a semi-ductile nature of the test material. Erosion increased with impact velocity and decreased with stand-off distance. In a dimensional analysis, erosion efficiency (η) and the relationship between friction and erosion were established. Test results were evaluated using Taguchis concept to minimize the observations needed, and ANOVA was used to identify interactions between tested parameters and to identify the most significant parameters. The S/N ratio indicates that there is only percentage of deviation between the predicted and experimental results. In further, sophisticated analyses and GMDH methods were employed, and surface damage was examined using scanning electron microscopy (SEM) to examine the nature of the wear behaviour.

Deposition on SS 316 at Different Gas Flow Rates Using Thermal CVD

A hot filament thermal chemical vapor deposition (CVD) reactor was used to deposit solid thin films on stainless steel 316 (SS 316) substrates at different flow rates of natural gas. The variation of thin film deposition rate with the variation of gas flow rate has been investigated experimentally. During experiment, the effect of gap between activation heater and substrate on the deposition rate has also been observed. Results show that deposition rate on SS 316 increases with the increase in gas flow rate. It is also observed that deposition rate increases with the decrease in gap between activation heater and substrate within the observed range. In addition, friction coefficient and wear rate of SS 316 sliding against SS 304 under different normal loads are also investigated before and after deposition. The experimental results reveal that improved friction coefficient and wear rate are obtained after deposition as compared to that of before deposition.

Phase Contamination Characterization of Stepwise-Built Functionally Graded Hydroxyapatite/Titanium (HA/Ti) Sintered under Various Atmospheres

Fourier Transform Infrared Spectroscopy (FTIR) and X-Ray Diffraction (XRD) test were utilized to detect the phase transformation of a HA/Ti Functionally Graded Material (FGM) prepared via Powder Metallurgy (PM) technique. The effects of oxygen (O2), nitrogen (N2), forming (N2+H2) and Argon (Ar) sintering atmospheres on the FGM specimens were examined by considering the gas flowing duration. It was found that the original metallurgical profile of pure Ti in HA/Ti FGM sintered under N2 atmosphere was almost preserved. However the carburization of the pure Ti was observed on the specimen. Medium alkyl halides (C-Br) and alkenes (-C=C-) stretches were detected, producing the dominant elements in the pure Ti layer of the specimen. The almost stable constituent element remains in the specimen sintered under flowing N2+H2 atmosphere as detected by XRD result. This proved the significance of controlling the sintering atmosphere during the entire sintering process. The results achieved reveal the high tendency of Ti and HA elements to react with the sintering environment, thus very precise furnace with controllable atmosphere is crucial for the fabrication of the HA/Ti FGM.

Study of Erosion Performance and Characterization of Ebonite Reinforced With Carbon Fibers

Composite materials have many applications at different mechanisms in industry. The erosion characteristics of new combinations of ebonite reinforced with carbon fiber were analyzed in this study. Randomly-shaped sand (SiO2) particles of various sizes (300–355, 355–500, and 500–600 μm) were selected erosive element. Tested conditions such as impact angles between 15 and 90°, impact velocities between 30 and 50 m/s, and stand-off distances 15–25 mm at surrounding room temperature were maintained. The highest level of erosion of the tested composite was obtained at 60° impact angle, which signifies the semi-ductile behavior of this material. Erosion showed an increasing trend with impact velocity and decreasing nature in relation to stand-off distance. Surface damage was analyzed using SEM to examine the nature of the erosive wear mechanism.

Modeling and Flow Analysis of Pure Nylon Polymer for Injection Molding Process

In the production of complex plastic parts, injection molding is one of the most popular industrial processes. This paper addresses the modeling and analysis of the flow process of the nylon (polyamide) polymer for injection molding process. To determine the best molding conditions, a series of simulations are carried out using Autodesk Moldflow Insight software and the processing parameters are adjusted. This mold filling commercial software simulates the cavity filling pattern along with temperature and pressure distributions in the mold cavity. In the modeling, during the plastics flow inside the mold cavity, different flow parameters such as fill time, pressure, temperature, shear rate and warp at different locations in the cavity are analyzed. Overall, this Moldflow is able to perform a relatively sophisticated analysis of the flow process of pure nylon. Thus the prediction of the filling of a mold cavity is very important and it becomes useful before a nylon plastic part to be manufactured.

Investigation of thin film deposition on stainless steel 304 substrates under different operating conditions

In recent times, friction and wear in relation to the deposited carbon films on the steel substrates are important issues for industrial applications. In this research study, solid thin films were deposited on the stainless steel 304 (SS 304) substrates under different operating conditions. In the experiments, natural gas (97.14% methane) was used as a precursor gas in a hot filament thermal chemical vapor deposition (CVD) reactor. Deposition rates on SS 304 substrates were investigated under gas flow rates 0.5 - 3.0 l/min, pressure 20 - 50 torr, gap between activation heater and substrate 3.0 - 6.0 mm and deposition duration 30 - 120 minutes. The obtained results show that there are significant effects of these parameters on the deposition rates on SS 304 within the observed range. Friction coefficient of SS 304 sliding against SS 314 was also investigated under normal loads 5 - 10 N and sliding velocities 0.5 - m/s before and after deposition. The experimental results reveal that in general, frictional values are lower after deposition than that of before deposition.

Influence of normal loads and sliding velocities on friction properties of engineering plastics sliding against rough counterfaces

Friction properties of plastic materials are very important under dry sliding contact conditions for bearing applications. In the present research, friction properties of engineering plastics such as polytetrafluoroethylene (PTFE) and nylon are investigated under dry sliding contact conditions. In the experiments, PTFE and nylon slide against different rough counterfaces such as mild steel and stainless steel 316 (SS 316). Frictional tests are carried out at low loads 5, 7.5 and 10 N, low sliding velocities 0.5, 0.75 and 1 m/s and relative humidity 70%. The obtained results reveal that friction coefficient of PTFE increases with the increase in normal loads and sliding velocities within the observed range. On the other hand, frictional values of nylon decrease with the increase in normal loads and sliding velocities. It is observed that in general, these polymers show higher frictional values when sliding against SS 316 rather than mild steel. During running-in process, friction coefficient of PTFE and nylon steadily increases with the increase in rubbing time and after certain duration of rubbing, it remains at steady level. At identical operating conditions, the frictional values are significantly different depending on normal load, sliding velocity and material pair. It is also observed that in general, the influence of normal load on the friction properties of PTFE and nylon is greater than that of sliding velocity.