CaRAlO 4 (R ‫؍‬ Nd, Sm, Y) ceramics with a K 2 NiF 4 structure were prepared by a solid-state reaction approach, and their microwave dielectric characteristics were evaluated, along with their microstructures. Dense CaNdAlO 4 , CaSmAlO 4 , and CaYAlO 4 ceramics were obtained by sintering at 1425°-1500°C in air for 3 h, and good microwave dielectric characteristics were achieved: (1) ‫؍‬ 18.2, Qf ‫؍‬ 17 980 GHz, f ‫؍‬ ؊52 ppm/°C for CaNdAlO 4 ; (2) ‫؍‬ 18.2, Qf ‫؍‬ 51 060 GHz, f ‫؍‬ ؊3 ppm/°C for CaSmAlO 4 ; and (3) ‫؍‬ 18.9, Qf ‫؍‬ 39 960 GHz, f ‫؍‬ 6 ppm/°C for CaYAlO 4 .

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This paper addressed the potential use of fibers from waste corn stalk as reinforcing materials in friction composites. The friction composites with different contents of corn stalk fibers were prepared, and their tribological and physio-mechanical behaviors were characterized. It was found that the incorporation of corn stalk fibers had a positive effect on the friction coefficients and wear rates of friction composites. Based on comparisons of the overall performance, FC-6 (containing 6 wt % corn stalk fibers) was selected as the best performing specimen. The fade ratio of specimen FC-6 was 7.8% and its recovery ratio was 106.5%, indicating excellent fade resistance and recovery behaviors. The wear rate of specimen FC-6 was the lowest (0.427 × 10−7 mm3 (N·mm)−1 at 350 °C) among all tested composites. Furthermore, worn surface morphology was characterized by scanning electron microscopy and confocal laser scanning microscopy. The results revealed that the satisfactory wear resistance performances were associated with the secondary plateaus formed on the worn surfaces. This research was contributive to the environmentally-friendly application of waste corn stalk.