{"title":"Functional Plasma-Synthesized Tungsten–Boron Coating on an Al2O3 Substrate","authors":"D. I. Balakhonov, S. V. Nikolenko","doi":"10.1134/S0036029524701441","DOIUrl":null,"url":null,"abstract":"<p><b>Abstract</b>—An experimental coating, which is formed during plasma synthesis of tungsten borides and the reduction of metallic tungsten from a mixture based on a scheelite concentrate and boric acid, is studied. The coating is formed on an Al<sub>2</sub>O<sub>3</sub> substrate. The step-by-step formation of borides on the substrate surface and the reduction of metallic tungsten using an electric arc plasma generator built in an experimental high-temperature synthesis facility is described. The coating on the substrate consists of reduced metallic tungsten and its borides synthesized in one technological stage during condensation from a dispersed vapor–drop state. To conduct a series of experiments, we designed a prototype of an indirect-acting plasma generator to generate an electric arc plasma flow with a specific power <i>g</i> > 10<sup>4</sup>–10<sup>5</sup> W/cm<sup>2</sup>. The mixture is destructurized and then sublimated in the form of a vapor–drop phase during the action of a high-temperature plasma flow on the complex structures of the mineral concentrate and its constituent tungsten oxide. Tungsten borides are synthesized during chemical transformations when a dispersed material is removed from a heated plasma flow, nucleation phases form, and the vapor–drop phase condenses on the substrate surface. The synthesis is also accompanied by significant boron sublimation from compounds, which leads to the reduction of metallic tungsten. The material formed during plasma synthesis forms a W–B system and structures, the physicochemical properties of which depend on the composition of the mixture, the flow density, and the plasma pressure and temperature. The results of chemical analysis of the particles forming the W–B coating as a solid solution of dendrites on the Al<sub>2</sub>O<sub>3</sub> substrate surface are presented. Using electron microprobe analysis, we determined the phase composition of the coating and revealed the presence of tungsten borides W<sub>2</sub>B<sub>5</sub>, WB<sub>2</sub>, W<sub>2</sub>B, and WB and metallic tungsten. The results of producing W–B coatings or films using mineral multicomponent raw materials can be useful in various high-tech industries, including the hydrometallurgical or chemical industry.</p>","PeriodicalId":769,"journal":{"name":"Russian Metallurgy (Metally)","volume":"2024 1","pages":"114 - 122"},"PeriodicalIF":0.4000,"publicationDate":"2025-01-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Russian Metallurgy (Metally)","FirstCategoryId":"5","ListUrlMain":"https://link.springer.com/article/10.1134/S0036029524701441","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q4","JCRName":"METALLURGY & METALLURGICAL ENGINEERING","Score":null,"Total":0}
引用次数: 0
Abstract—An experimental coating, which is formed during plasma synthesis of tungsten borides and the reduction of metallic tungsten from a mixture based on a scheelite concentrate and boric acid, is studied. The coating is formed on an Al2O3 substrate. The step-by-step formation of borides on the substrate surface and the reduction of metallic tungsten using an electric arc plasma generator built in an experimental high-temperature synthesis facility is described. The coating on the substrate consists of reduced metallic tungsten and its borides synthesized in one technological stage during condensation from a dispersed vapor–drop state. To conduct a series of experiments, we designed a prototype of an indirect-acting plasma generator to generate an electric arc plasma flow with a specific power g > 104–105 W/cm2. The mixture is destructurized and then sublimated in the form of a vapor–drop phase during the action of a high-temperature plasma flow on the complex structures of the mineral concentrate and its constituent tungsten oxide. Tungsten borides are synthesized during chemical transformations when a dispersed material is removed from a heated plasma flow, nucleation phases form, and the vapor–drop phase condenses on the substrate surface. The synthesis is also accompanied by significant boron sublimation from compounds, which leads to the reduction of metallic tungsten. The material formed during plasma synthesis forms a W–B system and structures, the physicochemical properties of which depend on the composition of the mixture, the flow density, and the plasma pressure and temperature. The results of chemical analysis of the particles forming the W–B coating as a solid solution of dendrites on the Al2O3 substrate surface are presented. Using electron microprobe analysis, we determined the phase composition of the coating and revealed the presence of tungsten borides W2B5, WB2, W2B, and WB and metallic tungsten. The results of producing W–B coatings or films using mineral multicomponent raw materials can be useful in various high-tech industries, including the hydrometallurgical or chemical industry.
摘要：研究了白钨矿精矿与硼酸混合等离子体合成硼化钨并还原金属钨的实验涂层。涂层是在Al2O3衬底上形成的。本文描述了在实验高温合成装置中使用电弧等离子体发生器在衬底表面逐步形成硼化物和还原金属钨的过程。衬底上的涂层由还原金属钨及其硼化物组成，这些金属钨及其硼化物是由分散的气滴状态在一个工艺阶段中冷凝合成的。为了进行一系列实验，我们设计了一个间接作用等离子体发生器的原型，以产生具有特定功率的电弧等离子体流。104 - 105 W /平方厘米。在高温等离子体流作用于矿物精矿及其成分氧化钨的复杂结构时，混合物被分解，然后以气滴相的形式升华。钨硼化物是在化学转化过程中合成的，当分散的材料从加热的等离子体流中移除时，形成成核相，并且气滴相在衬底表面凝结。该合成还伴随着化合物中显著的硼升华，这导致金属钨的减少。在等离子体合成过程中形成的物质形成了W-B体系和结构，其物理化学性质取决于混合物的组成、流动密度以及等离子体的压力和温度。给出了在Al2O3基体表面形成W-B涂层的枝晶固溶体的化学分析结果。利用电子探针分析了涂层的相组成，发现涂层中存在钨硼化物W2B5、WB2、W2B、WB和金属钨。使用矿物多组分原料生产W-B涂层或薄膜的结果可用于各种高科技工业，包括湿法冶金或化学工业。
期刊介绍：
Russian Metallurgy (Metally) publishes results of original experimental and theoretical research in the form of reviews and regular articles devoted to topical problems of metallurgy, physical metallurgy, and treatment of ferrous, nonferrous, rare, and other metals and alloys, intermetallic compounds, and metallic composite materials. The journal focuses on physicochemical properties of metallurgical materials (ores, slags, matters, and melts of metals and alloys); physicochemical processes (thermodynamics and kinetics of pyrometallurgical, hydrometallurgical, electrochemical, and other processes); theoretical metallurgy; metal forming; thermoplastic and thermochemical treatment; computation and experimental determination of phase diagrams and thermokinetic diagrams; mechanisms and kinetics of phase transitions in metallic materials; relations between the chemical composition, phase and structural states of materials and their physicochemical and service properties; interaction between metallic materials and external media; and effects of radiation on these materials.
求助内容：
应助结果提醒方式：
京公网安备 11010802042870号
