Microstructural Analysis of Dental Porcelain on Ni-Cr Alloy
| Autor: | Lin, S.H., 林世宏 |
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| Rok vydání: | 1996 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 84 The materials studied in this research were clinic-used dental Ni-Cr alloy andIPS-Classic V porcelains.It is known that two mechanisms,mechanical interlockand chemical reactions,control the bonding strength of alloys and porcelains.The contribution of the mechanical interlock is determined by the surface topography of the alloys,while the chemical reactions are influenced mainlyby the thickness of oxides layers.Both sandblasting and mechanical polishing were used to change the surface topography of the Ni-Cr alloy in the study.Also oxidation time and atmosphere were varied to produce different thickness of oxide layer.The adhesion of the Ni-Cr alloy/ porcelain was evaluaced by abending test,while the interfacial microstructure and chemistry were investigated by the state-of- the-art- transmission electron microscopy(TEM)and scanning electron microscopy(SEM).The experimental results revealed that:(1)A reaction zone,composed of crystalline KAlSi2O6,KAlSi3 O8,NaAlSi3O8 and TiOx identified by TEM and SEM,was observed near the Ni-Cr alloy/porcelain interfaces.(2)The number of anchor points at the interface plays an important role in controlling its bonding strength.It is also noted that the adhesion is improved with oxidation time and oxigen partial pressure, presumably due to the saturation of oxides near the interface.(3)According to the failure analysis of the bending test specimens,the fracture mode between the alloy and porcelain belongs to cohesive.(4)The optimun condition of surface pretreatment for the best adhesion between the Ni-Cr alloy and porcelain is to sabdblast and then oxide the alloy for 12minutes in air before enamelling. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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