Sean Landwehr University of Missorui-Rolla Ceramic Engineering

Processing of Alumina/Glass Laminates for Testing Crack Behavior at Elastic/Viscous Interfaces

Introduction

Crack behavior at an interface in materials is very important to characterize and understand. Crack behavior (propagation versus deflection) at an interface between two elastic materials is very well characterized, but no formal study on viscous/elastic interfaces has been done. To test this, an alumina/alkali zinc phosphate (AZP) glass laminate with alternating alumina and glass layers will be used. At elevated temperatures the glass will act as the viscous phase and the alumina will be the elastic material. It was the goal of this summer project to be able to produce these laminates for testing.

Primary Objectives

• Make a alumina/AZP glass laminates for investigating crack behavior at elastic/viscous interfaces

Approach

• Tape cast the alumina, use trial and error to find the best methodology for casting
• Find binder burnout and sintering parameters that yield good flat alumina sheets
• Use airbrush type sprayer to put down layer of glass and determine rate at which glass is put down
• Find appropriate heat treatment schedule with which to laminate these parts
• Find conditions that are needed for lamination

Findings

• Determined exact procedure to cast "good" tapes from this aqueous system
• Determined a binder burnout schedule and conditions, but could not make the alumina sheets flat enough (contributed to the inability to laminate samples)
• Determined the shrinkage of the alumina sheets from the green state to the sintered state
• The AZP glass can be sprayed to form the glass layers in the laminate
• The AZP glass is thermally compatible with the alumina when the layers are made thin enough
• The AZP showed trouble with bubbling, which prevented good lamination

Schematic representation of an alumina/AZP glass laminate.

Micrograph of a glass interface between two layers of alumina.

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Final Research Presentation