Properties of Spark Plasma Sintered Compacts and Magnetron Sputtered Coatings Made from Cr, Mo, Re and Zr Alloyed Tungsten Diboride

Abstract

To enhance the properties of tungsten diboride, we have synthesized and characterized solid solutions of this material with chromium, molybdenum, rhenium and zirconium. The obtained materials were subsequently deposited as coatings. Various concentrations of these transition metal elements, ranging from 0.0 to 24.0 at.%, on a metals basis, were made. Spark plasma sintering was used to synthesize these refractory compounds from the pure elements. Elemental and phase purity of both samples (sintered compacts and coatings) were examined using energy dispersive X-ray spectroscopy and X-ray diffraction. Microindentation was utilized to measure the Vickers hardness. X-ray diffraction results indicate that the solubility limit is below 8 at.% for Mo, Re and Zr and below 16 at.% for Cr. Above this limit both diborides (W,TM)B2 are created. Addition of transition metals caused decrease of density and increase of hardness and electrical conductivity of sintered compacts. Deposited coatings W1−xTMxBy (TM = Cr, Mo, Re, Zr; x = 0.2; y = 1.7–2) are homogenous, smooth and hard. The maximal hardness was measured for W-Cr-B films and under the load of 10 g was 50.4 ± 4.7 GPa. Deposited films possess relatively high fracture toughness and for WB2 coatings alloyed with zirconium it is K1c = 2.11 MPa m1/2.

Mechanical and Thermal Properties of W-Ta-B Coatings Deposited by High-Power Impulse Magnetron Sputtering (HiPIMS)

“…A cylindrical vacuum chamber (PREVAC, Rogów, Poland) equipped with a turbomolecular pump was used to perform all of the depositions. A single two-inch W 0.76 Ta 0.24 B 2.5 target prepared by the SPS technique [ 9 ] was used for the deposition of all coatings. The vacuum chamber was initially pumped by a turbomolecular and rotary pump down to a pressure of 5 × 10 −7 mbar.…”

“…The surface of each deposited film was also observed with a scanning electron microscope (SEM) JSM6010PLUS/LV JEOL microscope (JEOL, Akishima, Japan). As tungsten diborides are electrically conductive [ 9 ], no additional conductive layer was used. The chemical composition of the coatings was measured by energy dispersive spectroscopy (EDS).…”

Switching Properties of the Contact Coatings Based on Refractory Metals Alloys

“…As an alternative to these materials, contact coatings based on the binary alloys of refractory metals (Mo and W) with iron group metals (Ni and Co) [3,[12][13][14][15][16][17] are becoming increasingly common. These alloys exhibit high wear and corrosion stabilities and mechanical hardness [18][19][20][21].…”