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The Prediction of Fracture Toughness Properties of Bioceramic Materials by Crack Growth Simulation Using Finite Element Method and Morphological Analysis

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The Prediction of Fracture Toughness Properties of Bioceramic Materials by Crack Growth Simulation Using Finite Element Method and Morphological Analysis Proceedings of the 5th International Conference on Integrity-Reliability-Failure, Porto/Portugal 24-28 July 2016 Editors J.F. Silva Gomes and S.A. Meguid Publ. INEGI/FEUP (2016) PAPER REF: 6306 THE PREDICTION OF FRACTURE TOUGHNESS PROPERTIES OF BIOCERAMIC MATERIALS BY CRACK GROWTH SIMULATION USING FINITE ELEMENT METHOD AND MORPHOLOGICAL ANALYSIS Dariush Firouzi, Amirsalar Khandan (*) , Neriman Ozada Mech. Eng. Dept., Eastern Mediterranean University, North Cyprus, Gazimağusa, TRNC, Mersin, Turkey (*) Email: [email protected] ABSTRACT Various types of hydroxyapatite (HA) structures have received great attention of scientific researcher in biomaterials field. Also, it is common that HA is the essential inorganic materials in human hard tissue such as bone or teeth. Fracture toughness and micro-hardness properties are the important parameters required for the prediction of the mechanical performance of biomaterials structures before failures. The indentation micro-fracture method, which yields for the mode is critical stress intensity factor, KIC , is particularly useful when applied to brittle materials with low K IC . As fracture toughness is easy, fast technique and needs small testing equipments and area, here we represent the enhancement in hardness and toughness which is possible due to attain nano-crystalline size for HA powder using in powder, bulk or coating form, suitable sintering and variable composition. It is obvious that the HA hardness have close relationship with fracture toughness. Also, materials properties as the size of grain changes/reduced from micron to nano-meters influence the mechanical behaviour of biomaterials. As the current observation of papers illustrates, the HA toughness rise up to about 70% with compositing with other beneficial additives like Al 2O3, polyethylene, fluorine, diopside, zircon, akermanite, bioglass (BG), tungsten carbide (WC), carbon nanotube (NC), etc. Secondly, sintering improve the fracture toughness of the HA particles and other biomaterials as well. Also, one can say that sintering procedure effect the microstructure mechanisms for simultaneous enhancements in the hardness and fracture toughness of the bio-ceramics. In the current paper we predict the fracture toughness value changes to greater value with the morphology of the powder less in the case of amorphous materials like zircon. We consider the prediction method with Finite element analysis and gather data from other literatures. Keywords: Fracture toughness, sintered, non-sintered, powder, bulk, coating, biomaterials. INTRODUCTION The aim with the current paper was studying several literature regarding to fracture mechanics relates to the mechanism of products, geometry of materials, load application of bio-ceramics. It has been well recognized that bio-ceramics like hydroxyapatite (HA) is the basic inorganic materials human bone structure [1]. Research observation on in vitro test represented, it has the natural capacity to advance bone development [2]. Biomedical applications of bio-ceramic as well as in artificial bones implant are recently being clinically investigated. Various procedures (sintering, grain size, composition) have been examined in endeavors to enhance -897- Symposium_12: New Materials and Design Processes in Dental Medicine the mechanical properties for coating case and other specific applications [3-4]. This ability can be further improved by arranging of additive (various ions) into HA structure gradually by the encompassing bone showing cells which produced novel structured product [4]. As the second materials (phase) added to advanced biomaterial structure, other properties like mechanical behaviour like fracture toughness, micro-hardness, and thermal behaviour could be enhanced due to different synthesis technique and materials fabrications methods like mechanical activation (MA) [3, 7, 15], mechanochemical (MC) [4], sol-gel, precipitation, etc [4-6]. Strength properties of Ca 10 (PO 4)6(OH) 2 have been well investigated in several literature [6-10]. Because pure HA is very brittle compared to other ceramic, which is enough strong under compression test, however the materials properties is weak under tensile examination, micro hardness and shear stresses sample test [9]. However, high applications have been encountered with some limitation to non-load-bearing conditions because of its low mechanical properties, high dissolution rate and particularly low fracture toughness (low K IC ) [11-12]. In this literature, we investigate fracture toughness of HA in the form of powder composite and bulk dense materials. We present the materials and techniques that are possible to upgrade and improve these types of unique materials. Many experimental methods have been proposed to estimate roughness and fracture toughness of the coatings [12-13]. The 1/2 fracture toughness of HA is less than K IC <1 MPa m which is a principle disadvantage of this materials limits for bearing orthopaedic and clinical applications [14]. The indentation micro-fracture method, which yields for the different three mode like tensile force (mode-I), shear force (mode-II), and torsional force (mode-III) is critical stress intensity parameter, KIC. It is particularly useful when applied to brittle materials with low K IC . In addition, the biological evaluation of bio-ceramic shows that i n vitro and in vivo studies have close correlation with fracture toughness as mechanical behaviour [15]. Bioactivity and biocompatibility evaluation supporting a human cell reaction on synthesized materials and results showed that composites demonstrated no deleterious defect on some antigen expressions that play a vital role in the integrity fracture toughness (K IC ) was determined by an indentation technique as proposed by Laugier [16] and Evans [17]. The densification behaviour and mechanical properties of sintered and non-sintered HA effects on biological reaction as the several literature review illustrates [18-21]. As the HA biocompability and bioactivity proves with several characterization technique like cell culture and simulated body fluid (SBF) solution test, the mechanical characterization of HA is still a interesting topic in the recent years [9, 12]. Applying of calcium phosphates (CaPs) as artificial organ in human’s body has been constrained by low quality and low crack durability in the implant coating using in dental and orthopaedic prosthesis [3]. Furthermore, nanostructured bredigite (Ca 7MgSi 4O16 ) [22], fluorine [4], nanostructured diopside (CaMgSi 2O6) [3, 9], poly caprolactone, nanostructured akermanite (Ca 2MgSi 2O7) [1-3], polyethylene, Al 2O3, and tungsten carbide (WC), have discharge at a controlled rate to strength the HA arrangement for better mechanical reaction/behaviour. The crack durability and KIC for tungsten carbide (WC) is 6 MPa m 1/2 is accomplished with the SPS procedure. Additionally, some polymers like poly-imides have been composited and sintered to enhanced mechanical properties of primary and pure material [3]. Their outcomes also demonstrated that the mechanical and biological properties of the composites were better than those delivered by cold isostatic pressing (CIP) and conventional sintering. In every case study with proper fracture toughness, mechanical properties were observed that enhanced by compositions and sintering [6, 17]. Another factor which influence the fracture toughness of HA materials is the term of temperature which changes in higher heat condition between 800-1300°C for different biomaterials [1-3]. Applying these parameters like sintering, change in morphology, grain size, composition allows the HA to be utilize for suitable artificial organs under high load bearing situation [3, -898- Proceedings of the 5th International Conference on Integrity-Reliability-Failure 12]. Here we illustrate a valuable reference data to predict enhanced mechanical blends of HA at high temperatures with different particle size. Such composites plan to hold their valuable bioactive properties whilst giving more suitable mechanical properties to specific applications. In addition, the improved fracture toughness is connected with the microstructure of the compacts. The objective of the current report was to investigate the fracture toughness HA-added with some reinforcement and different sintering temperature and condition. EXPERIMENTAL PROCEDURE (FRACTURE TOUGHNESS) Fracture toughness (K IC ) play a vital role in the integrity mechanical reaction was determined by an indentation technique as proposed by Laugier and Evans [16] as following Eq. 1. 2/3 KIC = 0.015( ΑͯΏ (΄ ΄ Eq. (1) ) ) v Ώ ͼ √Αͧ Where c is the crack length, a, the half of the diagonal indention, E, the Young’s modulus, H, the hardness, P, the load applied and y is a polynomial function of c . A standout amongst the most imperative controlling parameter that must be considered a amid the preparing of hydroxyapatite is the determination of suitable powder solidification/sintering system to get a strong, high thickness HA body that is portrayed by having fine microstructure. The most ordinarily utilized union strategy is the traditional sintering technique. In any case, this strategy frequently requires long sintering calendar, ordinarily above 18–24 h which thus bring about coarse-grained microstructure and low mechanical properties. Thus, a more quick method, for example, microwave handling has been accounted for to create a thick sintered HA body that had fine microstructure combined with enhanced mechanical attributes.
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