Ceramics failure analysis

S. S. Scherrer, J. B. Quinn, G. D. Quinn, FL W. A. Wiscott, Fractographic Ceramic Failure Analysis Using the Replica Technique Two Case Studies, Dental Materials, 23 (11), (2006) 1397-1404. 

V. D. Frnchette, Failure Analysis of Brittle Materials, Advances in Ceramics, Vol. 28, The American Ceramic Society, Inc., Westervike, Ohio, 1990. 

The general principles involved in the failure analysis of ceramic materials are similar to the failure analysis of metals and alloys. Because of the brittle behavior of ceramic materials, failure may result in many pieces of the sample, which have to be reassembled in order to obtain information on the form of loading and the point of fracture initiation. The utmost care should be exercised in the reassembly of the fractured pieces so that the features of the fracture are preserved. 

The first and foremost step in failure analysis of ceramics consists of identifying the fracture origin and the type of cracking, which throws light on the type of failure such as failure due to impact, residual stress combined with load, thermal shock, improper machining, oxidation and corrosion. This is aided by micro- and macrofracto-graphy, examination of microstructure by SEM, chemical analysis and metallographic examination. 

W. D. Wolf, K. J. Vaidya, and L. Falter Francis, Mechanical properties and failure analysis of alumina-glass dental composites, Journal of the American Ceramic Society 79 1769-1776(1996). 

Microscopes have been used since the middle of the seventeenth century, and are now applied in all branches of scientific research, and are in routine use in education, hospitals, and industry. Indeed, it is considered that virtually all industrial products rely on the microscope at some stage, in development of the materials and techniques (metals, ceramics, polymers, food), in manufacture and testing, or in failure analysis. 

The fracture of ceramic balls in ceramic UHMWPE combination has been virtually zero. Fritsch and Gleitz (30) published a failure analysis on 4341 alumina ceramic heads articulating with 2693 alumina ceramic and 1464 polymer sockets implanted over 20 years (1974 to 1994), and concluded that the use of ball type neckless heads brought the fracture rate close to zero. The success rate of 10 years follow-up is normally above 90% for the elderly patient population. Stem and cup loosening are the causes of failure, where the consistent wear debris from UHMWPE and bone cement remain the problems. 

From the preceding discussion, it should be obvious that ceramic failure in any practical application implies the existence of a flaw that degrades the strength below the theoretical value and a stress sufficiently high to propagate that flaw. The intent of the failure analysis is, usually, to determine the nature of the flaw and, if possible, to ascertain how it was introduced. It is also desirable to determine the magnitude of the stress and how the stress was generated. 

Nondestructive evaluation of ceramics is currently useful for process development and improvement, failure analysis, and detection of gross defects. At this time, there is no NDE technique to find critical volume flaws quickly in arbitrarily shaped technical ceramics. 

Because ceramics are brittle, they are susceptible to catastrophic failure under mechanical load. The useful strength of a ceramic is determined by the flaw population stresses are concentrated at flaws, which cause cracks to propagate to failure. The critical property for ceramics in load-bearing uses is not the strength, but the fracture toughness—the resistance of the ceramic to crack propagation. The fracture surface of a ceramic bears the evidence of its failure. One must read the features in a fracture surface to understand the origin and path of the fracture. The case study by E. K. Beauchamp shows how much practical information can be obtained from ceramic fracture analysis. 

J. Lau, T. Castello, D. Shangguan, W. Dauksher, J. Smetana, R. Horsley, D. Love, I. Memis, and B. Sullivan, Failure Analysis of Lead-Free Solder Joints for a 1657 CCGA (Ceramic Column Grid Array) Package, Proceedings of MAPS 2004, Nov 2004... 

Poggie RA, Turgeon TR, Coutts RD. Failure analysis of a ceramic hearing acetabular component J Bone Joint Surg Am 2007 89(2)l567-75. 

This example relies on the identification of an element at the failure interface that can be used as a marker for a particular component in the formulation. More usual is the need to resort to high resolution spectroscopy. The data of O Fig. 10.8 relates to a radiation-cured adhesive being developed for the bonding of components to ceramic substrates for surface mount technology. Once again water reduced the adhesion below an acceptable level and XPS and ToF-SIMS analysis of the failure surfaces provides an indication of the cause of the failure. The adhesive has two major components an aromatic adhesive part and an aliphatic reactive diluent. Inspection of the high resolution Cls spectra from the adhesive side of the failure shows the expected Jt —> Jt shake-up satellite diagnostic of the aromatic component of the adhesive (Watts and Taylor 1995). The ceramic failure surface shows a small amount of carbon... 

It is sometimes necessary to acquire information regarding the cause of a ceramic fracture so that measures may be taken to reduce the likelihood of future incidents. A failure analysis normally focuses on determination of the location, type, and source of the... 

A partial answer to the first question has been provided by a theoretical treatment (1,2) that examines the conditions under which a matrix crack will deflect along the iaterface betweea the matrix and the reinforcement. This fracture—mechanics analysis links the condition for crack deflection to both the relative fracture resistance of the iaterface and the bridge and to the relative elastic mismatch between the reinforcement and the matrix. The calculations iadicate that, for any elastic mismatch, iaterface failure will occur whea the fracture resistance of the bridge is at least four times greater than that of the iaterface. For specific degrees of elastic mismatch, this coaditioa can be a conservative lower estimate. This condition provides a guide for iaterfacial desiga of ceramic matrix composites. 

Figure 3.33 Commercial ceramic package (a) high-voltage failure and (b) electrostatic analysis showing the high-field (3 MV/m) region.

PMDA-ODA on Al 0,. A minor improvement is noticed in the peel force of PMDA-ODA on Al20, when APS is applied to the surface. From the surface analysis results one can see that the APS was not retained on the IPA cleaned sapphire surface to any detectable level, which is likely the cause for no significant improvement in the peel force. The minor improvement in the results may have to do with a possible surface cleaning effect of the sapphire surface with APS solution. The data in Table 3 show that the failure locus has not changed significantly by the APS or T H exposure, being essentially in the polyimide film close to the polyimide/ceramic interface. 

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