Fabrication of cutting tools from functionally graded materials using Spark Plasma Sintering (SPS).

Author(s)

Marcelo Bertolete Carneiro

• Document type: Doctoral Thesis
• Press: São Paulo.
• Institution: Universidade de São Paulo (USP). Escola Politécnica (EP/BC)
• Defense date: 2014-01-23

Examining board members

Izabel Fernanda Machado; Amauri Hassui; Vânia Trombini Hernandes; Alessandro Roger Rodrigues; Humberto Naoyuki Yoshimura

• Advisor: Izabel Fernanda Machado

Abstract

The aim was fabricating cutting tools from functionally graded materials (FGM) by spark plasma sintering method (SPS), which allow heating and cooling rates higher than traditional methods, lower temperature and shorter time sintering, better energy control and high reproducibility. The materials used were ceramic powders based on alumina (Al2O3-ZrO2 and Al2O3-TiC) and cemented carbide (WC-Co), so that two inserts were developed, one of white ceramic (Al2O3-ZrO2) graded with cemented carbide and the other of mixed ceramic (Al2O3- TiC) graded with cemented carbide. The experimental methodology was developed from thermo-mechanical model application to estimate thermal residual stress along with tool thickness, study into the influence of SPS sintering parameters (Temperature and Pressure) over sintered quality (physical properties characterization, density), on the basis of these data, the best operating condition was chosen to fabricate workpieces for mechanical tests of flexural strength, hardness and fracture toughness, besides FGM inserts to machining tests in grey cast iron using turning operation. The results showed the machine parameter that mostly influenced density was Temperature; the AlTiC and AlZr FGMs got an increase of 126 and 73% in flexural strength in relation to their homogeneous ceramics. Following the materials sequence, the hardness was evaluated at 13.8 and 15.8 GPa, whereas the fracture toughness was 4.91 and 5.04 MPa.m1/2. For the machining tests, FGM AlZr cutting tools showed lower wear than FGM AlTiC ones; the cutting forces were influenced by Feed Rate and Cutting Speed. Finally, the Feed Rate was the variable that mostly influenced the roughness results. (AU)

• FAPESP's process: 10/00683-2 - Manufacture and wear evaluation in machining of materials produced by SPS (Spark Plasma Sintering)
• Grantee: Marcelo Bertolete Carneiro
• Support Opportunities: Scholarships in Brazil - Doctorate