M.N. Ahmad Fauzi

Advances in friction welding process: a review

Abstract Friction welding is now well established as one of the most economical and highly productive methods in joining similar and dissimilar metals. It is widely used in automotive and aerospace industrial applications. Friction welding is often the only viable alternative in this field to overcome the difficulties encountered in joining the materials with widely varying physical characteristics. This process employs a machine that is designed to convert mechanical energy into heat at the joint to weld using relative movement between workpieces, without the use of electrical energy or heat from other sources. This review deals with the fundamental understanding of the process. The focus is on the mechanism of friction welding, types of relative motions of the process, influence of parameters, heat generation in the process, understanding the deformation, microstructure and the properties of similar and dissimilar welded materials.

The Effect of Halloysite Nanotubes as a Novel Nanofiller on Curing Behaviour, Mechanical and Microstructural Properties of Ethylene Propylene Diene Monomer (EPDM) Nanocomposites

Halloysite nanotubes (HNTs) with hollow nanotubular structures were used as a new type of filler for ethylene propylene diene monomer (EPDM) matrix. EPDM/HNT nanocomposites were prepared using a two roll mill by adding 0 to 100 parts per hundred rubber (phr) HNTs. The results show that the tensile properties were increased with the addition of HNTs. The curing time decreased from 0 to 15 phr loading but subsequently increased from 15 to 100 phr, whereas the maximum torque exhibited an increasing trend from 0 to 100 phr. The addition of HNTs reduced the tan δmax and increased the storage modulus especially for the EPDM/HNT nanocomposites at high HNT loading.

The Effect of Carbon Black on the Properties of Magnetic Ferrite Filled Natural Rubber Composites

The effect of carbon black loading and type on the properties of ferrite filled natural rubber (NR) composites was investigated. The carbon black loading used was from 0 to 50 phr and ferrite loading was fixed at 80 phr. Carbon black grades N330 and N660 were used in this work. The scorch time decreased with the addition of carbon black in ferrite filled NR composites whereas the cure time increased. The tensile strength and elongation at break of ferrite filled natural rubber composites were found to decrease with the increase of both types carbon black loading. However, the stress at 100% elongation (M100) and stress modulus at 300% elongation (M300) exhibit an increasing trend. The microstructure showed that filler dispersion of ferrite filled natural rubber composites become poorer with increasing carbon black loading. The thermal stability was found to enhance with carbon black loading. The swelling test indicated that the swelling percentage reduced with increasing carbon black loading while at low loading enhanced the magnetic properties of the composites. The N330 carbon black filled NR composites showed longer scorch and cure times and better tensile properties, swelling resistance and magnetic properties but lower thermal stability than N660 carbon black filled NR composites.

First-principles LDA

Yttrium niobate () phosphor is studied experimentally and through first-principles calculations, in which the structural and electronic properties of are investigated using the local-density approximation LDA+U method. The absorption and luminescence experiments that were conducted on the host lattice show the band gap to be 4.1 eV. The LDA+U calculations allow us to obtain a band gap of 4.28 eV. The density of states obtained from the calculation shows that O 2p states contribute to the valence band. The lower conduction band is mainly composed of Nb 4d states, while the upper conduction bands involve contribution mainly from Y 4d states. The partial DOS of each atom in the niobate system is then compared to the ultraviolet (UV) and vacuum ultraviolet (VUV) spectra from A photoluminescence excitation (PLE) experiment to explain the nature of the bands observed.

+U

In this study, titanium tetrachloride (TiCl4) solution was successfully synthesized from titanium oxycarbonitride (TiOxCyNz) by means of chlorination process at low temperatures. Iron-free TiOxCyNz was prepared by carbothermal reduction and nitridation of Ilmenite (FeTiO3) with coal-75 wt. % PETas a reductant in a H2/N2 gas mixture. Aeration leaching via the Becher process for iron removal with NH4Cl solution was the preferred method for iron removal. The effect of reduction temperature on the synthesis of titanium oxycarbonitride (TiO0.02C0.13N0.85) powder suitable for iron removal has been investigated in the temperature range of 1150–1250°C. The reduced-nitrided ilmenite samples were characterized by XRD and SEM/EDX in terms of phases and morphology. The results showed that iron was formed in spherical and separated particles from TiOCN. Furthermore, the effects of temperature between 350–450°C and soaking time from 1 to 3 hours on the chlorination of iron-free titanium oxycarbonitride have been evaluated. The evaluation was based on design of experiment (DOE) to identify the significant variables on the extent of titanium extraction. DOE analysis based on weight loss validated by ICP tests, indicated a good extraction of titanium and synthesis of TiCl4 at 450°C.

calculations and luminescence study of YNbO4

In present study, the effects of the process parameters on chlorination of Titanium Carbide (TiC) was studied. Besides that, process parameters were investigated by using experimental design of experiment (DOE) and statistical analysis. The chlorination of the samples was carried out at temperatures between 400 to 500°C. Effects of three parameters, namely temperature, soaking time, and molar ratio of potassium permanganate (KMnO4) to hydrochloric acid (HCl) were investigated. The interaction, on the rate of chlorination of TiC were statistically evaluated by using DOE. The weight loss (wt. %) was the main response taken into account in this paper. The results of the experimental design indicated that the main significant factor for chlorination of TiC was higher temperature, soaking time and higher molar ratio of KMnO4 to HCl. DOE results have demonstrated that the highest extent of chlorination obtained at the highest weight loss (wt. %) was about 54.59 wt. % at 500°C with a soaking time of 180 minutes and KMnO4 to HCl molar ratio of 0.17 respectively. The amounted to a titanium extraction of about 96.39 %. On the other hand, the lowest wt. lost was 30.76 wt. % and this was obtained at 500°C for 120 minutes with KMnO4 to HCl molar ratio of 0.09 respectively. The results obtained from this work will be employed as a guide for the future studies on chlorination of nitrided/carburized Malaysian ilmenite or titanium oxycarbonitride. The final aim was to produce TiCl4 at low temperatures (≤500°C) using the latter samples. The experimental values are in good agreement with calculations from the statistical model.

The Preparation of Iron-Free TiCl4 from Reduced and Nitrided Ilmenite by Polyethylene Terephthalate

In this paper, production of TiCl4 from low-iron nitrided ilmenite samples at relatively low temperature using chlorine gas generated from the reaction between KMnO4 and HCl has been investigated. The effects of chlorination soaking time, potassium permanganate (KMnO4) to hydrochloric acid (HCl) molar ratio and aluminium powder catalyst in chlorine gas generation on titanium extraction from nitrided Malaysian ilmenite were examined. The low-iron nitrided Malaysian ilmenite contained titanium oxycarbonitride (TiOxCyNz) after carbothermal reduction and nitridation with subsequent leaching. Chlorination process was performed at 500°C for 30 – 60 minutes. Statistical analysis of the data was done by Design of Experiment (DOE) to identify the significant variables and their interactions. The results achieved in this study showed that the highest extent of chlorination was about 98.34% at 500°C for 60 minutes. The lowest extent of chlorination was about 68.51% obtained in KMnO4 to HCl molar ratio of 2.0 and 0.3...

Assessment of titanium carbide chlorination by statistical design

The green SrAl2O4:Eu2+, Dy3+ phosphor is a well-known persistent material for a wide region of applications such as lighting, traffic signs, interior decoration and medical application. Double activated SrAl2O4:Eu2+, Dy3+ with improved properties has been synthesized through solid state route at different firing atmospheres (reduction, vacuum, oxygen and CO2 wet gas) and heating times (1 h to 8 h). At the beginning the powders were heat treated for 2 h with a heating rate of 10°C/min. The phosphor prepared at different firing atmospheres and heating times exhibited a different wavelength and intensity of PL spectra. The emission intensity becomes stronger as the heating times increases from 1 h to 4 h. The difference found from these spectra maxima is rationalized based on the presence of intermediate phases and also on the diffusion activities of activator and co-activator in the host matrices.

Extraction of titanium from low-iron nitrided Malaysian ilmenite by chlorination

The present study elucidates the synthesis of magnesium ferrite magnetic nanocrystallites via hydroxylation–condensation reaction followed by an auto-combustion process. Nanocrystallites with diameter of 3–7 nm were successfully formed via this method. The ignition temperature of the redox reaction was apparently improved to 200°C by the modification of the pH of the metal aqueous solution. The crystallite size was altered by varying the hydrolysis parameters. The XRD analysis of the as-synthesized powder confirms the formation of a single-phase MgFe2O4 spinel structure. Importantly, the crystalline particles were obtained at low temperature without further calcination. The thermodynamic behavior of the precursor was characterized by DTA-TG. TEM observations showed the morphology and crystal structure of the nanocrystallites.

Luminescence of SrAl2O4:Eu2+, Dy3+ Ceramics Synthesized at Different Firing Condition

Iron-free titanium oxycarbonitride (TiOxCyNz) is a promising feedstock for production of titanium tetrachloride (TiCl4) at low temperatures. In this study, the effects of leaching variables such as temperature, time, particle size of staring material and concentration of the leaching solutions were evaluated on iron removal from nitrided Malaysian ilmenite by Becher process. The nitrided ilmenite was prepared by isothermal reduction with graphite at 1200 °C for 3 h in H2-N2 atmosphere. The aerated leaching experiments were conducted at 50–90 °C with addition of 0.3–2.0 wt% of NH4Cl catalyst. The highest extent of iron removal (XFe) was obtained at about 96.2% for the sample leached at 90 °C for 7 h with 2.0 wt% NH4Cl. The iron concentrate and titanium oxycarbonitride product were characterized by ICP-OES, XRD, XRF and SEM-EDX analyses. The results indicated that the aeration leaching process was a successful route to prepare low-iron titanium oxycarbonitride.