This study presents the mechanical properties of the Al-12Si matrix composite reinforced by various amounts of titanium carbide (TiC) and titanium nitride (TiN) particles. The wear behavior was investigated using a pin-on-disk wear testing machine with varying parameters such as normal load, reinforcement percentage, and track velocity. The results show that the wear of the Al-12Si matrix reinforced by 5, 10, and 15% TiC particles at 150 rpm with 15-N loads was 73x10-3,61x10-3,and 50.5x10-3 mm3, respectively, which is less than the wear for the same composites at 225 rpm with a 15-N load. This is because of the length of rubbing is more in the case of a higher speed. The results also show that the wear of the samples was decreased with an increasing percentage of reinforcement of TiN at both sliding speeds (150 and 225 rpm). The hardness of the Al-12Si/TiC composites with 5% TiC particles was found to be 50, and the hardness of same composites with 15% TiC reinforcements was 67, which is less than the hardness of Al-12Si/TiN composites with 15% TiN reinforcements. The composites before the wear test showed a uniform distribution of TiC and TiN particles through the cross section of the specimens and finer surfaces compared with matrix composite after the wear test. The mechanical properties such as hardness and wear resistance are observed to be increased considerably compared with the matrix composite.

Posted on: October 2013

Authored: Faiz Ahmad

Electromagnetic inference (EMI) is one of the most troubling back issues on which research is ongoing with various new combinations. There are many composites that have been utilized to provide shielding against EMI. Therefore, this review focused on the graphene, copper and nickel-based composites which are been utilized. As a study limitation, iron was not considered in the review as the focus was to explore the other metals which can come up as an emerging metals for EMI applications. It was revealed by the review that copper and nickel when combined with graphene give better shielding effectiveness. The effectiveness was not only achieved in X-band but also in the higher frequency range which shows it is of utmost importance in EMI applications. Therefore, more attention is utilized to these metals to further enhance their effectiveness.

Posted on: October 2022

Authored: Faiz Ahmad

Benefits achieved by the biodegradable magnesium (Mg) and zinc (Zn) implants could be suppressed due to the invasion of infectious microbial, common bacteria, and fungi. Postoperative medications and the antibacterial properties of pure Mg and Zn are insufficient against biofilm and antibiotic-resistant bacteria, bringing osteomyelitis, necrosis, and even death. This study evaluates the antibacterial performance of biodegradable Mg and Zn alloys of different reinforcements, including silver (Ag), copper (Cu), lithium (Li), and gallium (Ga). Copper ions (Cu2+) can eradicate biofilms and antibiotic-resistant bacteria by extracting electrons from the cellular structure. Silver ion (Ag+) kills bacteria by creating bonds with the thiol group. Gallium ion (Ga3+) inhibits ferric ion (Fe3+) absorption, leading to nutrient deficiency and bacterial death. Nanoparticles and reactive oxygen species (ROS) can penetrate bacteria cell walls directly, develop bonds with receptors, and damage nucleotides. Antibacterial action depends on the alkali nature of metal ions and their degradation rate, which often causes cytotoxicity in living cells. Therefore, this review emphasizes the insight into degradation rate, antibacterial mechanism, and their consequent cytotoxicity and observes the correlation between antibacterial performance and oxidation number of metal ions.

Posted on: September 2023

Authored: Faiz Ahmad

A 316L stainless steel (SS) alloy was developed with 1, 3, and 5 vol% titanium (Ti) reinforcement using the powder injection molding route, representing a low-cost option for biomedical implants. The investigation encompassed 1300 °C, 1350 °C, and 1380 °C sintering temperatures to ascertain the optimal physical and mechanical properties. Both sintering temperature and Ti influenced sintered density, and Ti mitigated the deleterious effects of residual carbon. At higher sintering temperatures, carbon and silicon tended to migrate and accumulate at the brink of Ti, leading to the formation of intermetallic compounds and increased brittleness. Dispersed Ti particles within the 316L matrix acted as nucleation sites and enhanced solid solubility with improved density. An astounding 96.11 % sintered density was achieved at 3 vol% Ti sample sintered at 1380°C. During the tensile test, 5 vol% Ti at 1380°C exhibited a low modulus of 58.9 GPa, which is highly desirable for orthopedic implant application. The XRD, SEM, tensile test, and nano-indentation results collectively provide evidence of beta-titanium formation during the sintering process. Conversely, the sample incorporating 3 vol% titanium, sintered at 1380°C, demonstrated a balanced performance, showcasing 432.94 + 12.8 MPa ultimate tensile strength, 3.06 = 0.17 % elongation, 74.2 GPa modulus, and 322 MPa and 423 MPa 0.2 % offset flexural and compressive yield strengths, respectively. Notably, an improvised wear resistance test underscored its aptitude for sliding wear resistance, solidifying its potential as a promising candidate for biomedical implants.

Posted on: December 2023

Authored: Faiz Ahmad