The metal injection molding (MIM) method was applied to manufacture a shaped charge liner (SCL) used for petroleum perforating bombs. Its application could overcome the drawback of heterogeneous density distribution prepared using the traditional powder metallurgy and spinning process. The sintering results showed that because of the limitation in the sintering temperature, the relative density of the W–Cu alloy shaped charge liners prepared by metal injection molding (MIM W–Cu SCLs) ranged from 48.05% at 1050 °C to 52.52% at 1100 °C, which was far below those prepared by spinning. Further increase to higher temperature led to the W–Cu separation, cracks, and distortion of the SCL. The explosive test proved that the shaped charge liners prepared by metal injection molding (MIM SCLs) could achieve comparable or even better penetration performance than those prepared by spinning. The particle size of tungsten played a significant role in the penetration performance in which the sample prepared from a −250-mesh tungsten powder showed the highest penetration depth, which was 18.44% deeper than that of the spinning process. From the observation of ballistic holes, the jet of the MIM SCL was composed of dispersed W–Cu particles without a slug. The diameters of the holes bored by the MIM SCLs were larger than those SCLs produced by spinning, which proved that the MIM SCL jet is noncoherent.

A study was conducted to evaluate the effect of nano-silica (NS) content on the strength and cytotoxicity of calcium-silicate-based root canal filling materials. In this experimental laboratory study, four types of calcium-silicate-based paste with different NS ratios were prepared and hydrated for seven or 28 days. The setting times, compressive strengths, and porosities were tested to determine the properties of the pastes. The residual NS and the calcium hydroxide (CH; Ca (OH)₂) content were investigated to analyze the hydration products. The experiments demonstrated that NS facilitates the hydration of calcium-silicate-based materials, enhances the formation of hydration products, and ensures effective porosity filling. Consequently, these findings suggest that NS contributes to the enhancement of the early compressive strength of calcium silicate root canal filling pastes. The addition of 9% NS enhanced the early compressive strength by 41.99% compared with the NS-free samples. Additionally, it was found that the test group without NS, as well as the test groups with 3% and 9% NS, exhibited mild cytotoxicity, while the test group with 15% NS exhibited moderate cytotoxicity. The observed cytotoxicity can be attributed to the increase in the ambient pH due to the production of CH during hydration. The findings of this study demonstrate that the early compressive strength of calcium-silicate-based root canal filling materials exhibits a substantial increase in response to the incorporation of NS, and that calcium-silicate-based root canal filling materials do not manifest significant levels of toxicity. NS improved hydration product formation and made efficient pore filling possible.

This study investigated the impact of particle size refinement on the hydration rate, permeability, and antimicrobial properties of tricalcium silicate (C₃S) in root canal applications. Four C₃S pastes with varying particle sizes were prepared and evaluated. Hydration experiments indicated that finer particles accelerated the early hydration rate, though agglomeration effects influenced the long-term behavior. Permeability assessments using simulated body fluid and confocal laser scanning microscopy revealed that smaller particles achieved significantly greater penetration depth and area into dentinal tubules. Antimicrobial tests against Enterococcus faecalis demonstrated that the 0.4 μm C₃S group exhibited superior bactericidal efficacy, with a notable improvement in penetration and antibacterial activity compared to the 12.8 μm group. These findings suggest that particle size reduction enhances the functional performance of C₃S-based sealers in endodontic therapy.