Interface Strength, Damage and Fracture between Ceramic Films and Metallic Substrates.

Lihong Liang,Luobing Wu,Huifeng Tan,Linfeng Chen

doi:10.3390/ma14020353

Abstract

Interface strength, damage and fracture properties between ceramic films and metallic substrates affect the service reliability of related parts. The films’ thickness, grain size and residual stress affect the interface properties and fracture behavior, thus related studies attract great attention. In this paper, the interface damage evolution and fracture behavior between ceramic films and metallic substrates were simulated by developing a three dimensional finite element model of alumina films on Ni substrates with cohesive elements in the interfaces. The interface fracture energy as a key parameter in the simulation was firstly determined based on its thermodynamic definition. The simulation results show the Mises stress distribution and damage evolution of the film/substrate structures during uniaxial tensile loading. Specially, when grain size of the films is in nanoscale, the interface strength increases obviously, agreeing with the previous experimental results. The effects of residual stress on interface properties was further simulated. The interface strength was found to decrease with increasing radial residual force and the axial residual pressure increases the interface strength. When the thickness of the films increases, the interface strength keeps a constant but the speed of interface damage becomes faster, that is, the thicker films show catastrophic fracture. The underlying mechanism of damage speed was analyzed. Understanding these size effects and the effects of residual stress is helpful to guide the design of related parts.

Highlights

Interfaces between ceramic films and metallic substrates have wide application, such as the interface between thermal growth alumina layer and nickel alloy substrate in serviced turbine blades of aeronautical engines [1], ceramic-metal joints in electronic components [2]and so forth
Residual thermal stress induced by fabrication of films affects interface properties and crack initiation, which has been analyzed and interface strength was found to increase with increasing residual compressive stress [6]
Nanocrystalline films was considered firstly based on advanced preparation technology [32], the interface fracture energy of 4.55 J/m2 was taken based on the calculation in Section 2 and the fracture displacement was assumed as 200 nm corresponding to several times of the grain size [24], the interface strength can be obtained to be about

Summary

Introduction

Interfaces between ceramic films and metallic substrates have wide application, such as the interface between thermal growth alumina layer and nickel alloy substrate in serviced turbine blades of aeronautical engines [1], ceramic-metal joints in electronic components [2]. The stability of residual stress in alumina films and its effect on mechanical properties was once studied [7]. The effects of the thickness of the film on the crack density in the film and the crack initiation strain were investigated based on a residual stress model [12]. How the crack modes in films depend on material properties and thickness ratio was studied by numerically analysis based on energy release rate [19]. Cracking evolution in coatings under three-point loading has been simulated based on two dimensional finite element method and damage process can be observed digitally [14]. Three dimensional (3D) stress analysis during interface fracture of film/substrate structure is more desired to capture damage evolution characteristics. The Mises stress evolution and interface damage characteristics was analyzed, the film thickness effect on the damage speed was revealed. The various effects of residual stress on interface strength was discovered

Interface Fracture Energy Between Alumina Films and Ni Substrates

Stress and Interface Damage Evolution

Thickness Effect of Alumina Films on Interface Damage and Fracture

Conclusions