Room Temperature Corrosion Behavior of ZrB2-HfB2 Solid Solutions in Acidic and Basic Aqueous Environments

Processing and Optical Behavior of Dense (Hf,Zr)B2 Solid Solutions for Solar Energy Receivers

“…By considering the high mutual solubility displayed by Zr-and Hfdiborides, the latter have been also combined in different proportions to form thermodynamically stable (Hf x Zr 1-x )B 2 solid solutions [5][6][7][8][9][10][11][12][13][14][15][16]. The methods proposed in the literature for their synthesis are chemical vapor deposition (CVD) [5,6], arc-melting [9], mechanically induced self-sustaining reaction [10], heat treatment of co-ball milled ZrB 2 and HfB 2 powders [11][12][13][14], molten salt route [15,16], carbothermal (CTR) and borohydride (BHR) reduction followed by flash sintering [7], and microwave co-assisted boro/carbothermal reduction [8]. Only few of them [7,[11][12][13][14] were addressed to the obtainment of bulk ceramics.…”

“…The methods proposed in the literature for their synthesis are chemical vapor deposition (CVD) [5,6], arc-melting [9], mechanically induced self-sustaining reaction [10], heat treatment of co-ball milled ZrB 2 and HfB 2 powders [11][12][13][14], molten salt route [15,16], carbothermal (CTR) and borohydride (BHR) reduction followed by flash sintering [7], and microwave co-assisted boro/carbothermal reduction [8]. Only few of them [7,[11][12][13][14] were addressed to the obtainment of bulk ceramics. McClane et al [11] produced 99.5% dense (Zr 0.97 Hf 0.03 )B 2 solid solutions by a multi-step hot pressing procedure (dwell temperature up to 2150 • C), from ball milled ZrB 2 , HfB 2 , and graphite powders.…”

“…McClane et al [11] produced 99.5% dense (Zr 0.97 Hf 0.03 )B 2 solid solutions by a multi-step hot pressing procedure (dwell temperature up to 2150 • C), from ball milled ZrB 2 , HfB 2 , and graphite powders. Individual borides were also used by Sitler et al [12][13][14] as precursors for the preparation of bulk (Hf x Zr 1-x )B 2 , with x = 0.2, 0.5, and 0.8. Initial powders were first ball milled for 3 h (ball to powder mass ratio equal to 10) and subsequently processed for 10 min by Spark Plasma Sintering (SPS) at 1700 • C, under vacuum conditions.…”

“…Initial powders were first ball milled for 3 h (ball to powder mass ratio equal to 10) and subsequently processed for 10 min by Spark Plasma Sintering (SPS) at 1700 • C, under vacuum conditions. The resulting sintered products displayed relative densities equal to 82.9 (x = 0.2), 76.2 (x = 0.5), and 76.5% (x = 0.8), and consisted of the expected solid solutions, with HfO 2 also detected by XRD analysis [12,13]. Among the three compositions investigated, (Hf 0.5 Zr 0.5 )B 2 samples showed the best corrosion resistance [12], and electrocatalytic properties [13].…”

“…The resulting sintered products displayed relative densities equal to 82.9 (x = 0.2), 76.2 (x = 0.5), and 76.5% (x = 0.8), and consisted of the expected solid solutions, with HfO 2 also detected by XRD analysis [12,13]. Among the three compositions investigated, (Hf 0.5 Zr 0.5 )B 2 samples showed the best corrosion resistance [12], and electrocatalytic properties [13]. Furthermore, the CTR and BHR routes were compared by Belisario et al [7] for the preparation of (Hf 0.5 Zr 0.5 )B 2 powders to be consolidated by Flash Sintering.…”