Microstructure, mechanical properties and chemical degradation of brazed AISI 316 stainless steel/alumina systems

• Type: Article in International Scientific Journal
• Date: 2008

Authors

Paiva, OC (Author) Other; Mário Adolfo Barbosa (Author) FEUP

Journal

The Journal is awaiting validation by the Administrative Services.

Title: MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING

Vol. 480

Pages: 306-315

ISSN: 0921-5093

Indexing

ISI Web of Knowledge - 10 Citations

Scopus - 13 Citations

Other information

Authenticus ID: P-003-ZDS

DOI: 10.1016/j.msea.2007.07.015

Abstract (EN): The main aims of the present study are simultaneously to relate the brazing parameters with: (i) the correspondent interfacial microstructure, (ii) the resultant mechanical properties and (iii) the electrochemical degradation behaviour of AISI 316 stainless steel/alumina brazed joints. Filler metals on such as Ag-26.5Cu-3Ti and Ag-34.5Cu-1.5Ti were used to produce the joints. Three different brazing temperatures (850, 900 and 950 degrees C), keeping a constant holding time of 20 min, were tested. The objective was to understand the influence of the brazing temperature on the final microstructure and properties of the joints. The mechanical properties of the metal/ceramic (M/C) joints were assessed from bond strength tests carried out using a shear solicitation loading scheme, The fracture surfaces were studied both morphologically and structurally using scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction analysis (XRD). The degradation behaviour of the M/C joints was assessed by means of electrochemical techniques. It was found that using a Ag-26.5Cu-3Ti brazing alloy and a brazing temperature of 850 degrees C, produces the best results in terms of bond strength, 234 +/- 18 MPa. The mechanical properties obtained could be explained on the basis of the different compounds identified on the fracture surfaces by XRD. On the other hand, the use of the Ag-34.5Cu-1.5Ti brazing alloy and a brazing temperature of 850 degrees C produces the best results in terms of corrosion rates (lower corrosion current density), 0.76 +/- 0.21 mu A cm(-2). Nevertheless, the joints produced at 850 degrees C using a Ag-26.5Cu-3Ti brazing alloy present the best compromise between mechanical properties and degradation behaviour, 234 +/- 18 MPa and 1.26 +/- 0.58 mu A cm(-2), respectively. The role of Ti diffusion is fundamental in terms of the final value achieved for the M/C bond strength. On the contrary, the Ag and Cu distribution along the brazed interface seem to play the most relevant role in the metal/ceramic joints electrochemical performance.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 10