Tungsten has been widely used in many industrial fields due to its excellent properties. However, owing to its characteristics of inherent brittleness at room temperature and high melting point, it is difficult to prepare tungsten parts with high complexity via traditional methods. In the present work, tungsten samples were prepared by laser powder bed fusion. The influence of each process parameter including laser power, scanning speed, and hatch spacing on the surface morphology, densification, and microstructure of tungsten samples was systematically investigated. The results showed that the use of the appropriate parameters, especially high laser power, can effectively improve the surface quality and obtain a dense surface. The tungsten samples with a relative density of 98.31% were obtained with optimized parameter combinations: a laser power of 300 W, scanning speed of 400 mm/s, and hatch spacing of 0.08 mm. Compared with scanning speed and hatch spacing, the laser power had a more obvious influence on the relative density. Additionally, for the grain morphology by microstructure inspection, elongated curved grains gradually transformed into fine straight columnar grains as the scanning speed increased. The hatch spacing would change the grain morphology slightly but had no significant effect on the grain size.
The preparation of refractory tungsten and tungsten alloys has always been challenging due to their inherent properties. Selective laser melting (SLM) offers a choice for preparing tungsten and tungsten alloys. In this work, 90W-7Ni-3Fe samples were prepared by selective laser melting and investigated. Different process parameter combinations were designed according to the Taguchi method, and volumetric energy density (VED) was defined. Subsequently, the effects of process parameters on densification, phase composition, microstructure, tensile properties, and microhardness were investigated. Nearly a full densification sample (≥99%) was obtained under optimized process parameters, and the value of VED was no less than 300 J/mm3. Laser power had a dominant influence on densification behavior compared with other parameters. The main phases of 90W-7Ni-3Fe are W and γ-(Ni-Fe), dissolved with partial W. In addition, 90W-7Ni-3Fe showed a high tensile strength (UTS = 1121 MPa) with poor elongation (<1%). A high average microhardness (>400 HV0.3) was obtained, but the microhardness presented a fluctuation along building direction due to the inhomogeneous microstructure.
Abstract. Although fused silica has better temperature characteristics than most materials, temperature drift is still one of the main error sources of a Cylindrical Vibratory Gyroscope (CVG) with a monolithic fused silica resonator. The change of temperature changes the characteristics of the material, at the same time changes the overall working status of gyroscope. In this paper, the influence of temperature on the vibration characteristics of fused silica cylindrical resonator is theoretically analyzed and experimentally verified. Results show that the vibration frequency is linearly related to temperature, which provides reference for temperature compensation and performance improvement of CVG.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.