dc.contributor |
Universitat Politècnica de Catalunya. Departament de Ciència dels Materials i Enginyeria Metal·lúrgica |
dc.contributor |
Llanes Pitarch, Luis Miguel |
dc.contributor.author |
Zakia, Rizki |
dc.date |
2013-02 |
dc.identifier.uri |
http://hdl.handle.net/2099.1/18829 |
dc.language.iso |
eng |
dc.publisher |
Universitat Politècnica de Catalunya |
dc.rights |
info:eu-repo/semantics/openAccess |
dc.subject |
Àrees temàtiques de la UPC::Enginyeria dels materials::Materials compostos |
dc.subject |
Àrees temàtiques de la UPC::Enginyeria dels materials::Materials ceràmics |
dc.subject |
Ceramic materials |
dc.subject |
Metals -- Mechanical properties |
dc.subject |
Carbides |
dc.subject |
Composite materials |
dc.subject |
Materials ceràmics |
dc.subject |
Metalls -- Propietats mecàniques |
dc.subject |
Carburs |
dc.subject |
Materials compostos |
dc.title |
Microstructural and Mechanical characterization of WC-Co cemented carbides |
dc.type |
info:eu-repo/semantics/bachelorThesis |
dc.description.abstract |
WC-Co cemented carbides are ceramic-metal composite materials made of carbides
embedded in a metal phase that acts as a binder. They exhibit an exceptional combination of
strength, toughness and wear resistance as a result of the extremely different properties of
their two constitutive phases. Consequently, cemented carbides have been positioned as
suitable options when selecting materials for tribomechanical applications, and their
implementation continues to gain a place in the market, particularly as structural components
and forming tools. Mechanical properties of hardmetals, especially hardness and toughness,
strongly depend on the nature, content and size of each microstructural constituent.
The aim of this project is to carry out a microstructural and mechanical characterization of
two different WC-Co grades with medium and coarse grain sizes and medium binder
content, as well as to conduct a detailed study of crack-microstructure interactions at the
crack tip during unstable crack propagation.
Microstructural characterization includes grain size, binder content, contiguity and mean free
path. Grain size distribution has been measured using two different techniques; by traditional
linear interception and by image analysis. It is found that image analysis way give similar
results in terms of mean carbide size and grain size distribution to those found with linear
interception. An intensive study on the grain size distribution as a function of the number of
measured grains has been also carried out.
The effect of the microstructure on the mechanical properties is discussed on the basis of a
fracture mechanics approach. Fracture of cemented carbides is governed by unstable
propagation of pre-existing flaws; hence, Weibull statistics are implemented as an effective
technique to evaluate the rupture strength and the reliability of the studied grades. After
rupture, a detailed fractographic analysis is conducted in order to identify the nature, size and
geometry of critical flaws. A detailed study of crack-microstructure interactions at the crack
tip is assessed by cross-sectioning and imaging the crack tip using the SEM/FIB tomography
technique.
This investigation led to the conclusion that the microstructure of each grade has a
determinant role since it affects directly the toughness and indirectly the size and distribution
of intrinsic defects. On the other hand, fracture process at the crack tip is governed by the
nucleation and growth of micro voids in the binder until it fractures by void coalescence. |
dc.description.abstract |
Incoming |