Cracking of porcelain coatings bonded to metal substrates of different modulus and hardness

Citation
H. Zhao et al., Cracking of porcelain coatings bonded to metal substrates of different modulus and hardness, J MATER RES, 16(5), 2001, pp. 1471-1478
Citations number
27
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Apllied Physucs/Condensed Matter/Materiales Science","Material Science & Engineering
Journal title
JOURNAL OF MATERIALS RESEARCH
ISSN journal
0884-2914 → ACNP
Volume
16
Issue
5
Year of publication
2001
Pages
1471 - 1478
Database
ISI
SICI code
0884-2914(200105)16:5<1471:COPCBT>2.0.ZU;2-0
Abstract
A preceding study of contact damage in a bilayer system consisting of a por celain coating on a stiff Pd-alloy substrate is here expanded to investigat e the role of substrate modulus and hardness. Bilayers are made by fusing t he same dental porcelain onto Co-, Pd-, and Au-alloy metal bases. Indentati ons are made on the porcelain surfaces using spheres of radii 2.38 and 3.98 mm. Critical loads to initiate cone fracture at the top surface of the por celain and yield in the substrate below the contact are measured as a funct ion of porcelain thickness. Radial cracks form at the lower surface of the coating once the substrate yield is well developed. By virtue of its contro lling role in the metal yield process, substrate hardness is revealed to be a key material parameter-substrate modulus plays a secondary role. A simpl e elasticity-based analysis for predetermining critical loads for a given b rittle/plastic bilayer system is presented.