Cermets based on FeAl–NbC from composite powders: Design of composition and processing

Abstract

The aim of this work is the design, processing and characterization of a metal-ceramic composite (cermet) with an iron -aluminum alloy as metallic matrix and NbC as ceramic phase. The cermet is obtained from a composite powder containing in situ formed NbCrich precipitates on an iron rich metal matrix. The starting powder was supplied by CBMM (Brazil), and it was produced by a synthesis process under development which introduces other metals such as Al, Si and Ti to the composition. Due to the in situ process, good bonding is expected between the carbide and the matrix. However it is necessary to study the processability of those complex particles and the transformations occurring during sintering to get the final microstructure. Thermodynamic studies by means of ThermoCalc ® software were performed to predict the phases stable with the starting composition and also the influence of Fe and C additions. Samples were produced by uniaxial pressing and vacuum sintering (PS), and also by Field Assisted Hot Pressing (FAHP). The processing parameters for PS processing, that is, sintering temperature and time were based on themodynamic simulations by ThermoCalc ® software together with thermal analysis. The powders were characterized by measuring density, particle size, carbon content and chemical composition; and consolidated samples by density and Vickers hardness. The microstructure and morphology of the powder and consolidated samples was analyzed by SEM. The addition of Fe and both C and Fe to the starting cermet composition provided good results as the final microstructure consisted essentially of NbC and Fe matrix. Abbreviations PS -Pressing and Sintering FAHP -Field Assisted Hot Pressing

Microstructure and mechanical properties of Cu-ZTA cermet prepared by vacuum hot pressing sintering

“…Cermets are widely used in cutting tools due to their excellent mechanical properties [1][2][3][4][5]. Cermets have high bonding strength, good formability, strong abrasiveness and can withstand large loads during processing [1,[6][7][8]. At present, cermet substrates are often made of metals such as Al, Cu and Fe.…”

“…In addition to improving the wettability of the interface, a suitable sintering process can also improve the interfacial bonding ability of ZTA and Cu. In the method of preparing copper-based cermet, powder metallurgy has become the first choice for the high density and low cost of the prepared cermet [1,33,34]. Vacuum hot pressing (VHP) is a manufacturing process for manufacturing cermets [18].…”

Ferramentas de corte a base de carbonetos cimentados (metais duros) aplicadas ao torneamento de aço AISI 4340 endurecido: contribuição ao estudo de substituição ao sistema WC-Co por uma alternativa NbC-Ni.

“…Outro ponto importante refere-se à toxicidade no processo de produção de ferramentas a base de WC-Co. Vários estudos realizados pelo REACH, que é o regulamento europeu relativo ao registro, à avaliação, à autorização e à restrição das substâncias e misturas químicas, mostram que as composições usadas para obter pó WC-Co por processo de redução, como trióxido de tungstênio (WO3) e tetróxido de tricobalto (Co3O4), receberam várias classificações e rótulos relatados devido à sua relação com toxicidade mutagênica e carcinogênica (WOYDT; MOHRBACHER, 2014;WOYDT et al, 2016;FRANCO et al, 2015;MOHRBACHER et al, 2016;TOLLER, 2017). A Tabela 1 apresenta um extrato do sumário de classificação de saúde e segurança destas substâncias realizado pelo REACH (MOHRBACHER et al, 2016).…”

“…Recentemente, especial atenção foi dada ao uso de nióbio para aplicações de ferramentas de corte, usando carboneto de nióbio (NbC) como a principal fase dura do substrato da ferramenta de corte (WOYDT; MOHRBACHER, 2014;WOYDT et al, 2016;HUANG et al, 2015;HUANG et al, 2017 WOYDT et al, 2016;FRANCO et al, 2015;TOLLER, 2017).…”

“…Somado a isto, o alto custo e a constante valorização do preço do minério, uma consequência do fato de ser amplamente extraído em áreas que foram afetadas por conflitos, tem motivado a busca por material mais barato (MIDTGARD;BINDERUP, 1994;PRAKASH et al, 1980;MOHRBACHER, 2014;WOYDT et al, 2016;FRANCO et al, 2015;TOLLER, 2017;MIRANDA et. al, 2021).…”