Xingke Zhao

Electrical discharge erosion in liquid media is a simple, effective technique to generate multi-scale metallic particles. An experimental investigation was conducted to determine the main machining parameters which contribute to particle size (PS) and size distribution (SD) in WEDM of bronze. Five factors, including three-level built-in processing patterns, wire speed and dielectric medium, are selected as control parameters using an orthogonal array L₁₆(4⁵) Taguchi method, PS and SD of produced powders are the measure of quality. The goal is to obtain micron-scale spherical metal powder with uniform particle size. Results show that cutting-section pattern is the most significant factor, and the electrolyte is the least. The PS and SD performance of the optimized powders is significantly improved by using Taguchi method. Spherical bronze powder with particle size of d₁₀ 11.05 μm, d₅₀ 31.13 μm and d₉₀ 67.48 μm are prepared using the optimized WEDM process parameter, which is A3–B4–C3–D1–E1 including dielectric medium water, cutting class 4, cutting division 3, cutting Sect. 1 and wire speed 200 μm/s. The research confirms that WEDM can be used to produce micron-scale metallic powders, providing cheap and high-quality metallic powders for the metal additive manufacturing industry.

Sucrose, as a precursor of carbon, and titanium powders were used to prepare TiC powders by a spray-drying/precursor-pyrolysis method. Using the powders, TiC/Ti composite coatings were deposited by reactive plasma spraying. The results show that submicron-sized TiC is formed. The TiC phases have three kinds of crystal morphology: spherical TiC with a diameter of about 600 nm, dendrite TiC with a primary dendrite spacing of about 450 nm and a secondary arm spacing of about 150 nm, and cellular-dendrite TiC with a width of about 120 nm and a length of about 600 nm. The TiC/Ti coatings exhibit high microhardness and excellent wear resistance, which is about 2–3 times and about 200 times higher than that of TC4 alloys, respectively.