ABSTRACT

The importance of evaluating the nanomechanical properties for the bioactive HAp ceramic coatings is highlighted by the large amount of data that have been reported [1-16] for the nanohardness [1-4, 7-11, 13-16] and Young’s modulus [2-14, 16] of both HAp [1-13, 16] and HAp composite [9, 14] coatings. Such coatings have been deposited by plasma spraying [1-6], laser-assisted process [8-10, 12, 16], sol-gel process [14, 15], sputtering [10, 11], and other thermal spraying techniques [9, 13, 15]. The measurements were made using a wide variety of nanoindenters, e.g., a Berkovich tip [1-7, 9-11, 13-15] or a Vickers tip [8] and a spherical indenter [16]. However, systematic studies of both the nanohardness and elastic modulus as measured by the nanoindentation technique under a variety of applied loads on HAp coating are scarce [2, 3]. It was also found in general that the scatter in data was very high for the plasma-sprayed coatings, presumably due to the highly heterogeneous and porous structure of the coatings [2, 17-19]. However, the quantification of such scatter in the perspective of data reliability has not been attempted for MIPS-HAp coatings. Therefore, in this chapter we shall try to assess how we can quantify the data reliability in terms of a Weibull distribution for the nanohardness and elastic modulus on the plan section of MIPS-HAp coatings as measured by the nanoindentation technique with a Berkovich indenter under a variety of loads in the range of 10-1000 mN [21]. Further details about this aspect are discussed in Chapter 50.