Preparation of High-entropy Boride Powders for Plasma Spraying by Inductive Plasma Spheroidization

doi:10.15541/jim20250008

Abstract

Abstract:

Fabrication of feedstock powders is a critical technology that directly influences the microstructure and performance of plasma-sprayed coatings. Conventional boron thermal reduction methods for synthesizing high-entropy boride powders encounter several limitations such as prolonged processing time, impurity contamination, and inability to obtain spray-ready powders. In this work, an inductive plasma spheroidization (IPS) process was employed to fabricate (Zr_1/4Hf_1/4Ta_1/4Ti_1/4)B₂ high-entropy powders for plasma spraying in contrast to the other two traditional powder preparation routes. The morphology, internal structure, particle size distribution, density, and other fundamental properties of powders were systematically characterized. The effects of different powder fabricating processes on the microstructure and fundamental properties of high-entropy boride powders were systematically investigated, thereby validating the broad applicability of this methodology for synthesizing high-entropy boride powders. The results demonstrate that using commercial micron-sized boride powders as precursors, a hybrid process combining mixing, spray drying, sintering with IPS facilitates the fabrication of high-entropy powders with homogeneous elemental distribution. The resulting powders exhibit spherical morphology, smooth surfaces, high internal density, and high apparent/tap density. Further experiments on synthesizing different high-entropy borides with varied compositions confirm the extensive applicability of this method. The formation mechanism of high-entropy solid solutions is elucidated through first-principles calculations combined with the unique characteristics of IPS process. This work proposes a promising method for fabricating high-entropy ceramic powders suitable for plasma-spray coatings.

Key words: inductive plasma spheroidization, high entropy ceramic powder, boride, powders for spray

CLC Number:

TQ174

YU Leyangyang, ZHAO Fangxia, ZHANG Shuxin, XU Yixiang, NIU Yaran, ZHANG Zhenzhong, ZHENG Xuebin. Preparation of High-entropy Boride Powders for Plasma Spraying by Inductive Plasma Spheroidization[J]. Journal of Inorganic Materials, 2025, 40(7): 808-816.

Figures/Tables 12

Fig. 1 Flow chart for preparation of different (Zr1/4Hf1/4Ta1/4Ti1/4)B2 powders

Table 1 Process parameters for powder preparation by inductive plasma spheroidization

Parameter	Value
Second gas (H₂)/slpm	30-60
Primary gas (Ar)/slpm	120-150
Chamber pressure/psig	3-7
Powder feed rate/(g·min^-1)	20-40

Fig. 2 Cellular modeling of binary transition metal boride

Fig. 3 XRD patterns of (Zr1/4Hf1/4Ta1/4Ti1/4)B2 powders prepared by different processes

Fig. 4 SEM images and EDS mappings of MIX (a1-a4), BTR (b1-b4), and IPS (c1-c4) powders

Table 2 Particle size distribution, apparent and tap densities of three kinds of (Zr1/4Hf1/4Ta1/4Ti1/4)B2 powders

Powder	D₁₀/μm	D₅₀/μm	D₉₀/μm	D₉₇/μm	Apparent density/(g·cm^-3)	Tap density/(g·cm^-3)
MIX	16.53	33.14	61.72	77.85	1.93	2.38
BTR	19.65	34.92	66.66	79.61	2.25	2.82
IPS	11.08	28.65	56.61	73.30	4.40	4.77

Fig. 5 TG-DSC curves of (Zr1/4Hf1/4Ta1/4Ti1/4)B2 powders prepared by three processes (a) and Gibbs free energy for the oxidation reaction of single-component borides (b) Colorful figures are available on website

Fig. 6 XRD patterns of (Zr1/3Nb1/3Ti1/3)B2, (Zr1/4Ta1/4Nb1/4Ti1/4)B2, and (Zr1/5Cr1/5Ta1/5Nb1/5Ti1/5)B2 powders prepared by IPS

Fig. 7 SEM images and EDS mappings of (Zr1/3Nb1/3Ti1/3)B2 (a), (Zr1/4Ta1/4Nb1/4Ti1/4)B2 (b), and (Zr1/5Cr1/5Ta1/5Nb1/5Ti1/5)B2 (c) powders prepared by IPS Table shows the corresponding element contents (in atom) of spot 1-spot 6

Fig. 8 Schematic diagram of inductive plasma spheroidization

Fig. 9 Atomic radii and ground-state energies of different transition metals Me

Table 3 Density functional theory energies (Etot) and cohesive energies (Ecoh) of (Me0.5Zr0.5)B2

(Me_0.5Zr_0.5)B₂	E_tot/(eV·atom^-1)	E_coh/(eV·atom^-1)
(Ti_0.5Zr_0.5)B₂	-49.14	-7.29
(V_0.5Zr_0.5)B₂	-49.06	-7.06
(Cr_0.5Zr_0.5)B₂	-48.38	-6.62
(Nb_0.5Zr_0.5)B₂	-50.57	-7.37
(Mo_0.5Zr_0.5)B₂	-50.22	-7.07
(Hf_0.5Zr_0.5)B₂	-51.37	-7.49
(Ta_0.5Zr_0.5)B₂	-52.20	-7.59
(W_0.5Zr_0.5)B₂	-51.72	-7.32

References 27

[1]	陈玉峰, 洪长青, 胡成龙, 等. 空天飞行器用热防护陶瓷材料. 现代技术陶瓷, 2017, 38(5): 311.
[2]	PADTURE N P. Advanced structural ceramics in aerospace propulsion. Nature Materials, 2016, 15(8): 804. DOI PMID
[3]	JIN X, FAN X, LU C, et al. Advances in oxidation and ablation resistance of high and ultra-high temperature ceramics modified or coated carbon/carbon composites. Journal of the European Ceramic Society, 2018, 38(1): 1.
[4]	NI D, CHENG Y, ZHANG J, et al. Advances in ultra-high temperature ceramics, composites, and coatings. Journal of Advanced Ceramics, 2022, 11(1): 1.
[5]	OSES C, TOHER C, CURTAROLO S. High-entropy ceramics. Nature Reviews Materials, 2020, 5(4): 295.
[6]	CAI F Y, NI D W, DONG S M. Research progress of high-entropy carbide ultra-high temperature ceramics. Journal of Inorganic Materials, 2024, 39(6): 591.
[7]	HOQUE M S B, MILICH M, AKHANDA M S, et al. Thermal and ablation properties of a high-entropy metal diboride: (Hf_0.2Zr_0.2Ti_0.2Ta_0.2Nb_0.2)B₂. Journal of the European Ceramic Society, 2023, 43(11): 4581.
[8]	WANG H X, LIU Q M, WANG Y G. Research progress of high entropy transition metal carbide ceramics. Journal of Inorganic Materials, 2021, 36(4): 355. DOI
[9]	GUO L X, TANG Y, HUANG S W, et al. Ablation resistance of high-entropy oxide coatings on C/C composites. Journal of Inorganic Materials, 2024, 39(1): 61.
[10]	XU Y, PAN X, HUANG S, et al. Effect of solid oxidation products on the ablation mechanisms of ZrC and HfC based coatings above 2000 ℃. Journal of Materials Research and Technology, 2023, 22: 1900.
[11]	XU Y, ZHENG W, DAI M, et al. Effect of TaSi₂ addition on long-term ablation behavior of HfB₂-SiC coating. Journal of the European Ceramic Society, 2023, 43(14): 5802.
[12]	XU Y, HUANG S, HAN D, et al. Effect of different SiC/TaSi₂ contents on ablation behavior of ZrB₂ coating. Corrosion Science, 2022, 205: 110424.
[13]	PAN X, NIU Y, LIU T, et al. Ablation behaviors of ZrC-TiC coatings prepared by vacuum plasma spray: above 2000 ℃. Journal of the European Ceramic Society, 2019, 39(11): 3292.
[14]	杜仲, 霍威, 赵帅, 等. YSZ粉末致密度对涂层性能的影响. 中国钨业, 2022, 37(1): 42.
[15]	陈伟文. 粉末球形度对超音速火焰喷涂制备不锈钢涂层组织及性能的影响. 中国机械, 2019(11): 50.
[16]	GAO P H, YANG G J, CAO S T, et al. Heredity and variation of hollow structure from powders to coatings through atmospheric plasma spraying. Surface and Coatings Technology, 2016, 305: 76.
[17]	SUN S, LIU Y, MA Z, et al. Fabrication of ZrB₂-SiC powder with a eutectic phase for sintering or plasma spraying. Powder Technology, 2020, 372: 506.
[18]	LI G, WANG D, WU Y, et al. The solid solution and microstructural evolution of WC doped Hf-Ta-C powders by induction plasma spheroidization. Powder Technology, 2023, 419: 118338.
[19]	PAN X, XU X, NIU Y, et al. Relationship analysis on particle-coating-ablation property of UHTC coatings fabricated by plasma spray technique. Ceramics International, 2021, 47(3): 3808.
[20]	LIU B, DUAN H, LI L, et al. Microstructure and mechanical properties of ultra-hard spherical refractory high-entropy alloy powders fabricated by plasma spheroidization. Powder Technology, 2021, 382: 550.
[21]	SHEN X Q, LIU J X, LI F, et al. Preparation and characterization of diboride-based high entropy (Ti_0.2Zr_0.2Hf_0.2Nb_0.2Ta_0.2)B₂-SiC particulate composites. Ceramics International, 2019, 45(18): 24508.
[22]	XU Y, YU L, ZHAO T, et al. Composition design of oxidation resistant non-equimolar high-entropy ceramic materials: an example of (Zr-Hf-Ta-Ti)B₂ ultra-high temperature ceramics. Journal of Advanced Ceramics, 2024, 13(12): 2087.
[23]	POST B, GLASER F W, MOSKOWITZ D. Transition metal diborides. Acta Metallurgica, 1954, 2(1): 20.
[24]	LIU H, ZHAO X. Thermal conductivity analysis of high porosity structures with open and closed pores. International Journal of Heat and Mass Transfer, 2022, 183: 122089.
[25]	BABAEI H, MCGAUGHEY A J H, WILMER C E. Effect of pore size and shape on the thermal conductivity of metal-organic frameworks. Chemical Science, 2017, 8(1): 583. DOI PMID
[26]	LIU G A, WANG H L, FANG C, et al. Effect of B₄C content on mechanical properties and oxidation resistance of (Ti_0.25Zr_0.25Hf_0.25Ta_0.25)B₂-B₄C ceramics. Journal of Inorganic Materials, 2024, 39(6): 697.
[27]	HOU X, CHOU K C. Quantitative investigation of oxidation behavior of boron carbide powders in air. Journal of Alloys and Compounds, 2013, 573: 182.