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Abstract(s)
Os revestimentos compósitos Al-12Si/NbC foram produzidos por deposição assistida por laser em um substrato de liga Al-7Si. A microestrutura e a resistência ao desgaste dos revestimentos foram avaliadas em comparação com as propriedades do substrato e da liga da matriz. A resistência ao desgaste foi avaliada usando testes de deslizamento reciproco de configuração esfera sobre o plano, em que foram usados como contra-corpos esferas do aço crómio AISI 52100, aço inox 316L, carboneto de tungsténio (WC) e óxido de alumínio (Al2O3). A microestrutura dos revestimentos é constituída por partículas de NbC dispersas numa matriz de liga Al-12Si. A matriz é constituída por dendrites primárias de α-Al e mistura eutéctica α-Al/Si. O reforço com partículas de NbC induz um aumento considerável na dureza média do material da matriz de (85 ± 1) HV a (152 ± 40) HV e na respetiva resistência ao desgaste. Os mecanismos de desgaste envolvem oxidação, adesão com deformação plástica e delaminação e dependem do contra-corpo utlizado.
Al-12Si/NbC composite coatings were produced by laser-assisted deposition on a substrate of Al-7Si alloy. The microstructure and wear resistance of the coatings were evaluated in comparison to the properties of the substrate and the matrix alloy. The wear resistance was evaluated using reciprocating sliding tests in a configuration of sphere over-a-plan and as counter-body spheres of AISI 52100 chromium steel, AISI 316L stainless steel, tungsten carbide (WC) and alumina (Al2O3). The coatings microstructure consists of NbC particles dispersed in an Al-12Si alloy matrix. The matrix consists of primary dendrites of α-Al and α-Al/Si eutectic mixture. The reinforcement with NbC particles induces a considerable increase in the average hardness of the matrix material from (85 ± 1) HV to (152 ± 40) HV and in the respective wear resistance. The wear mechanisms involve oxidation, adhesion with plastic deformation and delamination and depend of the counter-body used.
Al-12Si/NbC composite coatings were produced by laser-assisted deposition on a substrate of Al-7Si alloy. The microstructure and wear resistance of the coatings were evaluated in comparison to the properties of the substrate and the matrix alloy. The wear resistance was evaluated using reciprocating sliding tests in a configuration of sphere over-a-plan and as counter-body spheres of AISI 52100 chromium steel, AISI 316L stainless steel, tungsten carbide (WC) and alumina (Al2O3). The coatings microstructure consists of NbC particles dispersed in an Al-12Si alloy matrix. The matrix consists of primary dendrites of α-Al and α-Al/Si eutectic mixture. The reinforcement with NbC particles induces a considerable increase in the average hardness of the matrix material from (85 ± 1) HV to (152 ± 40) HV and in the respective wear resistance. The wear mechanisms involve oxidation, adhesion with plastic deformation and delamination and depend of the counter-body used.
Description
Dissertação apresentada para cumprimento dos requisitos necessários à obtenção do grau de Mestre em Engenharia de Produção
Keywords
Deposição assistida por laser Compósito Al-12Si/NbC Desgaste por deslizamento Laser-assisted deposition Al-12Si/NbC composite Sliding wear