Open Access Research Article Issue
Influence of nano-mechanical evolution of Ti3AlC2 ceramic on the arc erosion resistance of Ag-based composite electrical contact material
Journal of Advanced Ceramics 2024, 13 (2): 176-188
Published: 31 January 2024

Al-containing MAX phase ceramic has demonstrated great potential in the field of high-performance low-voltage electrical contact material. Elucidating the anti-arc erosion mechanism of the MAX phase is crucial for further improving performance, but it is not well-understood. In this study, Ag/Ti3AlC2 electrical contact material was synthesized by powder metallurgy and examined by nanoindentation techniques such as constant loading rate indentation, creep testing, and continuous stiffness measurements. Our results indicated a gradual degradation in the nano-mechanical properties of the Ti3AlC2 reinforcing phase with increasing arc erosion times, although the rate of this degradation appeared to decelerate over arc erosion times. Specifically, continuous stiffness measurements highlighted the uneven mechanical properties within Ti3AlC2, attributing this heterogeneity to the phase’s decomposition. During the early (1–100 times) and intermediate (100–1000 times) stages of arc erosion, the decline in the nano-mechanical properties of Ti3AlC2 was primarily ascribed to the decomposition of Ti3AlC2 and limited surface oxidation. During the later stage of arc erosion (1000–6200 times), the inner region of Ti3AlC2 also sustained arc damage, but a thick oxide layer formed on its surface, enhancing the mechanical properties and overall arc erosion resistance of the Ag/Ti3AlC2.

Open Access Research Article Issue
One-dimensional core-sheath Sn/SnOx derived from MAX phase for microwave absorption
Journal of Materiomics 2024, 10 (3): 531-542
Published: 17 August 2023

One-dimensional (1D) metals are highly conductive and tend to form networks that facilitate electron hopping and migration. Hence, they have tremendous potential as microwave-absorbing (MA) materials. Traditionally, 1D metals are mainly precious metals such as gold, silver, nickel, and their preparation methods often have low yield and are not environmentally friendly, which has limited the exploration in this area. Herein, the unique nanolaminate structure and chemical bond characteristics of Ti2SnC MAX phase is successfully taken advantages for large-scale preparation of Sn whiskers, and then, core-sheath Sn/SnOx heterojunctions are obtained by simply annealing at different temperatures. The heterojunction annealed at 500 ℃ possesses favorable MA performance with an effective absorption bandwidth of 5.3 GHz (only 1.7 mm) and a minimum reflection loss value of −51.97 dB; its maximum radar cross section (RCS) reduction value is 29.59 dB·m2, confirming its excellent electromagnetic wave attenuation ability. Off-axis electron holography is used to visually characterize the distribution of charge density at the cylindrical heterogenous interface, confirming the enhanced interfacial polarization effect. Given the diversity of MAX phases and the advantages of the fabrication method (e.g., green, inexpensive, and easily scalable), this work provides significant guidance for the design of 1D metal-based absorbers.

Open Access Research Article Issue
Vegard’s law deviating Ti2(SnxAl1−x)C solid solution with enhanced properties
Journal of Advanced Ceramics 2023, 12 (8): 1655-1669
Published: 02 August 2023

The achievement of chemical diversity and performance regulation of MAX phases primarily relies on solid solution approaches. However, the reported A-site solid solution is undervalued due to their expected chemical disorder and compliance with Vegard’s law, as well as discontinuous composition and poor purity. Herein, we synthesized high-purity Ti2(SnxAl1−x)C (x = 0–1) solid solution by the feasible pressureless sintering, enabling us to investigate their property evolution upon the A-site composition. The formation mechanism of Ti2(SnxAl1−x)C was revealed by thermal analysis, and crystal parameters were determined by Rietveld refinement of X-ray diffraction (XRD). The lattice constant (a) adheres to Vegard’s law, while the lattice constant (c) and internal free parameter (zM) have noticeable deviations from the law, which is caused by the significant nonlinear distortion of Ti6C octahedron as Al atoms are substituted by Sn atoms. Also, the deviation also results in nonlinear changes in their physicochemical properties, which means that the solid solution often exhibits better performance than end members, such as hardness, electrical conductivity, and corrosion resistance. This work offers insights into the deviation from Vegard’s law observed in the A-site solid solution and indicates that the solid solution with enhanced performance may be obtained by tuning the A-site composition.

Open Access Research Article Issue
Slip casting and pressureless sintering of Ti3AlC2
Journal of Advanced Ceramics 2019, 8 (3): 367-376
Published: 03 August 2019

Slip casting and subsequent pressureless sintering (PLS) allow the preparation of complex-shaped and large-sized Ti3AlC2 components for many potential applications. The behaviors of the suspensions, green compacts, and sintered samples of Ti3AlC2 were studied in this paper. The optimized condition of 1 wt% of arabic gum as dispersant at pH = 10 results in a Ti3AlC2 suspension for slip casting Ti3AlC2 green compacts without macro defects or cracks. The sintering temperature and Al4C3 embedding powder are found to dominate the properties of the sintered Ti3AlC2 samples. The Ti3AlC2 sample sintered at 1450 ℃ for 1.5 h with Al4C3 embedding powder reaches the best properties, namely 95.3% relative density, hardness of 4.18 GPa, thermal conductivity of 29.11 W·m-1·K-1, and electrical resistivity of 0.39 μΩ·m. The findings in this work may pave the way for the application of MAX phases with large size and complex shape.

Open Access Research Article Issue
Preparation and arc erosion properties of Ag/Ti2SnC composites under electric arc discharging
Journal of Advanced Ceramics 2019, 8 (1): 90-101
Published: 13 March 2019

New Ag/Ti2SnC (Ag/TSC) composites with uniform microstructure were prepared by powder metallurgy. The superior wettability between Ag and Ti2SnC was confirmed with a contact angle of 14°. Arc erosion properties of Ag/10wt%Ti2SnC (Ag/10TSC) and Ag/20wt%Ti2SnC (Ag/ 20TSC) contacts were investigated under 400 V/100 A/AC-3 and compared with Ag/CdO contact. The Ag/10TSC contact exhibited comparable arc erosion property to Ag/CdO contact. The fine arc erosion resistance was attributed to the good wettability between Ti2SnC and Ag, the good heat-conducting property of Ag/10TSC, and the slight decomposition of Ti2SnC that absorbed part of electric arc energy. The excessive Ti2SnC significantly decreased the thermal conducting property of the Ag/20TSC composite, resulting in the severe heat accumulation that decomposed Ti2SnC and deteriorated arc erosion property. The oxidation behavior of Ti2SnC under high electric arc temperature was also studied and then an arc erosion mechanism was proposed to get a comprehensive understanding on the arc erosion property of Ag/TSC composites.

Open Access Research Article Issue
Synthesis and formation mechanism of titanium lead carbide
Journal of Advanced Ceramics 2018, 7 (2): 178-183
Published: 17 April 2018

Ti2PbC was synthesized for the first time by pressureless reaction synthesis using Ti/Pb/TiC as starting materials at a heating rate of 2 ℃/min and holding at 1370 ℃ for 2 h in a tube furnace protected by Ar atmosphere. The effects of starting powders, heating rates, and holding temperatures on the formation of Ti2PbC were investigated. It was found that elementary mixture of Ti/Pb/C or higher heating rates fail to form Ti2PbC. The decreased lattice parameters in the synthesized Ti2PbC indicated the existence of Pb vacancies in the compound. A reaction mechanism was proposed to explain the formation of Ti2PbC.

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