Optimization of NaCl based spray corrosion test process parameters of heat treated hybrid metal matrix composites

ABSTRACT. Aluminium hybrid metal matrix composites (AHMMCs) have widely employed in aerospace, transportation, and automotive applications since for their excellent mechanical qualities and high corrosion resistance. In this research, Al8079 is selected as a matrix material. The titanium diboride (TiB2) is selected as hard reinforcement and molybdenum disulfide (MoS2) is used as soft reinforcement. The Al8079/15 wt.% TiB2/x wt.% MoS2 (x = 0, 2.5, 5 and 7.5) HMMCs are fabricated by using stir casting. The composites are heat treated under T6 condition. The density and micro hardness tests are conducted. The optimization on NaCl based spray corrosion test process parameters is done using grey relational analysis (GRA). The selected input process parameters are Al8079/15 wt.% TiB2/wt.% MoS2 (x = 0, 2.5 and 5), pH value of NaCl solution (x = 6, 9 and 12), hang time (x = 24, 48, and 72 h) and pressure (x = 0.7, 0.9 and 1.1 kg/cm2). The selected response parameters are micro hardness, mass loss and wear loss. The L9 Taguchi design is used for optimization. The wear test is conducted at the constant speed of 0.5 m/s, loading rate of 20 N and the sliding distance of 1000 m. The percentage of improvement of GRG from initial setting to experimental is 10.4%.   KEY WORDS: Reinforcement, Stir casting, Optimization, GRA, NaCl Bull. Chem. Soc. Ethiop. 2022, 36(4), 903-914.                                                         DOI: https://dx.doi.org/10.4314/bcse.v36i4.1

Comparative evaluation of penetration depth and push-out bond strength of C points and gutta percha using bioceramic & AH plus sealer: An Invitro study

The present study was done in the Department of Conservative dentistry and Endodontics, KSR Institute of Dental Science and Reaearch. The aim of the present study was to evaluate & compare the penetration depth & push out bond strength of Bioceramic & AH Plus sealer with C points and gutta percha. 80 mandibular premolar teeth were used & decoranated. All teeth were prepared using protaper rotary file system upto F3 file size using Xmart plus (DENTSPLY Maillefer). The irrigation solution used after each instrumentation were NaOCl, 17% EDTA & normal saline. Samples were grouped into four based on the core material & root canal sealer used of each group containing 20 number of teeth. In Group I, obturation done using C Points & MTA plus (bioceramic sealer); Group II – C Points & AH Plus sealer ; Group III – Gutta Percha & MTA plus (bioceramic sealer) & Group IV – Gutta percha & AH Plus sealer. Horizontal sections of 2 mm thickness were made from coronal, middle & apical region of samples. Specimens were analysed using confocal laser scanning electron microscopy for the depth of penetration of sealers and the push out bond strength test was done with the help of universal testing machine at a cross head speed of 0.5 mm / min. The findings of the present study can be summarized as follows: Push out bond strength & penetration depth values were not significantly different between the tested groups, except between MTA plus sealer with C points & AH plus sealer with C points in the coronal third push-out bond strength. Based on the mean values: 1. MTA plus sealer & AH plus sealer showed better depth of penetration when used with C points than with GP. 2. MTA plus sealer exhibited better bond strength with C Points and Gutta Percha. But, AH Plus performed better with Gutta Percha when compared with C Points. 3. Although AH plus sealer with C points showed better depth of penetration, it exhibited the least bond strength. CONCLUSION: 1. The present study showed that the depth of penetration can be directly correlated with the bond strength, but not with all sealers & core materials. 2. Within the limitations of this study, it can be concluded that Bioceramic (MTA plus) sealer with C points showed greater penetration depth & greater bond strength

Postabortion family planning operations research study in Perm, Russia

EngenderHealth, the Population Council’s FRONTIERS program, and the Research Center of Obstetrics, Gynecology, and Perinatology of the Russian Academy of Medical Sciences, with support from the Perm Health Departments, undertook an operations research study to test models for increasing contraceptive use and reducing the repeat abortion rate among abortion clients in Perm, Russia. The study also assessed the direct and indirect costs of abortion and contraceptive use incurred by women in the year following their index abortion (the abortion which took place the day of entry into the study). The findings of the study were significant for the training interventions and dissemination of educational materials and job aids. Results of the study indicate that institutionalizing family planning counseling for all abortion clients is a low-cost quality-enhancing intervention for the existing healthcare system that does not require increased personnel, purchase of expensive equipment, or remodeling of healthcare facilities. Because of this, the counseling interventions included in the study can be easily replicated in any Russian oblast or city healthcare facility

Newtonian Heating Effects of Oldroyd-B Liquid Flow with Cross-Diffusion and Second Order Slip

The current study highlights the Newtonian heating and second-order slip velocity with cross-diffusion effects on Oldroyd-B liquid flow. The modified Fourier heat flux is included in the energy equation system. The present problem is modeled with the physical governing system. The complexity of the governing system was reduced to a nonlinear ordinary system with the help of suitable transformations. A homotopy algorithm was used to validate the nonlinear system. This algorithm was solved via MATHEMATICA software. Their substantial aspects are further studied and reported in detail. We noticed that the influence of slip velocity order two is lower than the slip velocity order one

Mathematical modelling of nitrate removal from water using a submerged membrane adsorption hybrid system with four adsorbents

© 2018 by the authors. Excessive concentrations of nitrate in ground water are known to cause human health hazards. A submerged membrane adsorption hybrid system that includes a microfilter membrane and four different adsorbents (Dowex 21K XLT ion exchange resin (Dowex), Fe-coated Dowex, amine-grafted (AG) corn cob and AG coconut copra) operated at four different fluxes was used to continuously remove nitrate. The experimental data obtained in this study was simulated mathematically with a homogeneous surface diffusion model that incorporated membrane packing density and membrane correlation coefficient, and applied the concept of continuous flow stirred tank reactor. The model fit with experimental data was good. The surface diffusion coefficient was constant for all adsorbents and for all fluxes. The mass transfer coefficient increased with flux for all adsorbents and generally increased with the adsorption capacity of the adsorbents

Enhanced removal of nitrate in an integrated electrochemical-adsorption system

© 2017 Elsevier B.V. The electrochemical (EC) method of removing pollutants in water is a widely used process in water and wastewater treatment. An EC-adsorption integrated system was investigated to test whether the simultaneous removal of nitrate by the two processes would be better than removal utilising the individual EC and adsorption methods. In the integrated system, an adsorbent (ion exchange resin - Dowex 21k XLT) was placed inside a stainless steel box that served as an anode with a Cu plate as cathode. In an experiment using 2 L nitrate solution containing 20 mg N/L and 2 g adsorbent the rate of nitrate removal in the integrated system was initially fast with 35% removed in 30 min, though slowing down later. The rate of removal increased with increasing current, voltage and pH up to 7 but decreased as the distance between the electrodes also increased. The optimum nitrate removal of 67% was obtained at pH 7, 1 A, and 31 V for a distance of 1 cm between the electrodes after 180 min. The amount of nitrate removed fell when sulphate was present in the integrated system due to sulphate competing with nitrate for adsorption. Concentration of ammonium produced by nitrate reduction in the EC system was reduced in the presence of adsorbent. Nitrate removal in the integrated system is approximately equal to the sum of the removals in the two individual processes

Analytical study of radiative casson nanoliquid flow with heat absorption

The divergence of thermally radiative MHD flow of a Casson nanofluid over a stretching paper alongside heat absorption. The governing non linear equations are remodeled into a nonlinear ODE’s. The HAM is adopted to find the series solution. The changes of pertinent parameters are analyzed with diagrams and tables. The fluid velocity is controlled by suction and it develops with injection. The local Nusselt number rapidly suppresses with increasing the magnetic field parameter in heat generation case

Computational analysis of third-grade liquid flow with cross diffusion effects: application to entropy modeling

The key goal of this current study is to analyze the entropy generation with cross diffusion effects. The third-grade type non-Newtonian fluid model is used in this study. The current flow problem is modelled with stretching plate. Modified Fourier heat flux is replaced the classical heat flux. The appropriate transformation is availed to convert the basic boundary layers equations into ODEs and then verified by homotopy algorithm. The consequences of various physical quantities on temperature, velocity, entropy and concentration profile are illustrated graphically