Ceramic Materials PDF

Ch5 Ceramic Materials D r. N u r N a b i l a h S h a h i d a n BF 2.18 This Photo by Unknown Author is licensed under CC BY ...

Ch5 Ceramic Materials D r. N u r N a b i l a h S h a h i d a n BF 2.18 This Photo by Unknown Author is licensed under CC BY  FR Outline: 1. Introduction 2. Desired properties of bioceramics 3. Type of bioceramics 4. Degradation of ceramic. Add a footer 2  FR 1.0 INTRODUCTION A ceramic is an inorganic non-metallic solid made up of either metal or non-metal compounds (they are most frequently oxides, nitrides, and carbides) that have been shaped and then hardened by heating to high temperatures. Properties of ceramics: Hard Brittle : Allow for little deformation before failure Can withstand high compression stress. Typically, crystalline in nature. Good electric and thermal insulator. Good aesthetic appearance Transparency to light. Ref : Materials Science and Engineering, Callister, 9th ed  FR 2.0 DESIRED PROPERTIES OF BIOCERAMICS In order to be classified as a bioceramic, the ceramic material must exceed such properties: 1. Should be biocompatible 2. Appropriate mechanical properties for specific application 3. Degradable vs stable 4. Should be bioactive for its lifetime in host 5. Should be nontoxic 6. Should be noncarcinogenic (cancer cause potential) 7. Should be nonallergic 8. Should be non inflammatory  FR 3.0 TYPEs OF BIOCERAMICS 3.2 NON-INERT BIOCERAMICS (RESORBABLE) BIOCERAMICS 3.1 INERT (NON- 3.3 SURFACE REACTIVE / RESORBABLE) BIOCERAMICS BIOACTIVE BIOCERAMICS Notes Type of Absorbable : Capable of being absorbed or taken in through the pores of a surface. Bioceramic Here, it is used to describe materials that will disappear from the implantation location over time.  FR 3.1 INERT (NON-ABSORBABLE) BIOCERAMICS Have all the six (6) Maintain their physical Resist corrosion and desired properties of and mechanical wear implantable properties while in host. bioceramics. Typically used as structural-support Have a reasonable Alumina, Zirconia and implant such as bone fracture toughness. Carbon plates, bone screw and femoral heads.  FR 3.1 INERT (NON-ABSORBABLE) BIOCERAMICS 3.1.1 ALUMINA (Al203) The main source of alumina or aluminium oxide is bauxite and native corundum. Highly stable oxide – very chemically inert Low fracture toughness and tensile strength – high compression strength Very low wear resistance Quite hard material, varies from 20 to 30 GPa. Notes: Bauxite and corundum is type of minerals  FR 3.1 INERT (NON-ABSORBABLE) BIOCERAMICS Mechanical properties requirement: Property Definition Compressive strength: 4 -5 Gpa Tensile Strength The maximum stress a material can withstand while being stretched or Flexural strength : > 400MPa pulled before breaking. Elastic modulus: 380 GPa Compressive Strength The maximum stress a material can withstand while being compressed Density : 3.8 – 3.9 g/cm3 or squeezed before failing. The maximum stress a material can withstand while being bent. Also Flexural Strength known as bending strength or modulus of rupture. A material's ability to resist crack Fracture Toughness propagation. Measures the energy required to grow a crack. Measures a material's stiffness, specifically the ratio of stress to Elastic Modulus strain in the elastic deformation region. Also known as Young's modulus.  FR 3.1 INERT (NON-ABSORBABLE) BIOCERAMICS ALUMINA High hardness + low friction + low wear+ inert to in vivo environment Ideal material for use in: Orthopaedic joint replacement component, e.g. femoral head of hip implant Orthopaedic load-bearing implant Implant coating Dental implants 3.1 INERT (NON-ABSORBABLE) BIOCERAMICS FR 3.1.2 ZIRCONIA (Zr202) Pure zirconia can be obtained from chemical conversion of zircon, which is an abundant mineral deposit.  FR 3.1 INERT (NON-ABSORBABLE) BIOCERAMICS Has a high melting temperature and chemical stability. The bending strength and fracture toughness are 2-3 and 2 times greater than alumina. The improved mechanical properties plus excellent biocompatibility and wear properties make this material the best choice the new generation of orthopaedic implant. Has already widely use to replace alumina and metals.  FR 4.1 INERT (NON-ABSORBABLE) BIOCERAMICS 4.1.3 CARBON Carbon can be made in many allotropic forms: Crystalline diamond Graphite Nanocrystalline glassy carbon Quasicrystalline pyrolitic carbon Only pyrolitic carbon is widely utilized for implant fabrication. Pyrolitic? Normally used as surface coating  FR 3.2 NON-INERT BIOCERAMICS (RESORBABLE) Chemically broken down by the body and degrade The resorbed material is replaced by endogenous tissue Chemicals produced as the ceramic is resorbed must be able to be processed through the normal metabolic pathways of the body without evoking any deleterious effect. Synthesize from chemical (synthetic ceramic) or natural sources (natural ceramic)  FR 3.2 NON-INERT BIOCERAMICS (RESORBABLE) Examples of Resorbable Bioceramics: Synthetic: 1. Calcium phosphate :- Hydroxyapatite (HA) Tricalcium phosphate 2. Bioactive glass Natural: Biocoral  FR 3.2 NON-INERT BIOCERAMICS (RESORBABLE) Synthetic ceramic Calcium phosphate and Hydroxyapatite ▪Calcium phosphate has been used to make artificial bone. Recently, this material has been synthesized and used for manufacturing various forms of implant as well as for solid or porous coatings on other implants. ▪There are mono-, di-, tri-, and tetra-calcium phosphates, in addition to the hydroxyapatite and whitlockite which have ratios of 5/3 and 3/2 for calcium and phosphorus (Ca/P), respectively. The stability in solution generally increases with increasing Ca/P ratios. synthetic FR CHIMIA 2010, 64, No. 10  FR Nanomaterials 2017, 7(6), 138; Synthetic HA : Hydrothermal technique Natural HA Applied Surface Science, 413, 2017,129-139  FR 3.2 NON-INERT BIOCERAMICS (RESORBABLE) Calcium phosphate and Hydroxyapatite Hydoxyapatite is the most important among the calcium compounds since it is found in natural hard tissues as mineral phase. Hydroxyapatite acts as a reinforcement in hard tissues and is responsible for the stiffness of bone, dentin, and enamel. Hydroxyapatite (HA) has a similar properties with mineral phase of bone and teeth. The mineral part of bone and teeth is made of a crystalline form of calcium phosphate similar to hydroxyapatite [Ca10(PO4)6(OH)2]. Important properties of HA: Excellent biocompatibility Form a direct chemical bond with hard tissue  FR 3.2 NON-INERT BIOCERAMICS (RESORBABLE) ▪Polycrystalline hydroxyapatite has a high elastic modulus (40–117 GPa). ▪Hard tissues such as bone, dentin, and dental enamel are natural composites that contain hydroxyapatite (or a similar mineral) as well as protein, other organic materials, and water. ▪Enamel is the stiffest hard tissue with an elastic modulus of 74 GPa, and it contains the most mineral. ▪Dentin (E = 21GPa) and compact bone (E = 12~18 GPa) contain comparatively less mineral. Joon B Park, Introduction to biomaterials  FR 3.2 NON-INERT BIOCERAMICS (RESORBABLE) 5.2.2 Natural ceramic At a temperature of 900 °C the coral was 5.2.2.1 Biocoral found to decompose all the carbonate phases. The pre-heated coral is converted Corals transformed into HA into hydroxyapatite by a chemical exchange Biocompatible reaction with di-ammonium phosphate under hydrothermal conditions. Facilitate bone growth Used to repair traumatized bone, replaced disease bone and correct various bone defect. Bone scaffold  FR 3.3 BIOACTIVE BIOCERAMICS Direct and strong chemical bond with tissue Fixation of implants in the skeletal system Low mechanical strength and fracture toughness Examples: Glass ceramics Hydroxyapatite  FR Direct and strong chemical bond with tissue 3.3 BIOACTIVE BIOCERAMICS Ability to Osteoint integrate with egration surrounding bone Capable of BIOACTIVE Osteoin promoting BIOCERAMICS ductive differentiation of cell TYPES Support bone growth and Osteocon facilitate ingrowth ductive of surrounding Add a footer bones 22  FR 3.3 BIOACTIVE BIOCERAMICS Glass ceramics Glass-ceramics are crystalline materials obtained by the controlled crystallization of an amorphous parent glass. Controlled crystallisation requires: specific compositions heat-treatment Controlled nucleation Controlled crystallization will growth of crystal of small uniform size  FR 3.3 BIOACTIVE BIOCERAMICS Type of glass ceramic Bioglass ® (45S5:45 wt% SiO₂, 24.5 wt% CaO, 24.5 wt% Na₂O, and 6.0 wt% P₂O₅) Ceravital® Both are SiO2, CaO, Na2O and P2O5 systems Bioglass composition manipulated to induce direct bonding with the bone Must simultaneously form a calcium phosphate and SiO2 – rich film layer on surface of ceramic for this to happen With correct composition will bond with bone in It is important to recognize that relatively approximately 30 days small changes in the composition of a biomaterial can affect dramatically Bioactive Glass>60% SiO2: Chemically stable but not whether it is bioinert, resorbable, or bioactive45% SiO2: Very bioactive bioactive  FR 3.3 BIOACTIVE BIOCERAMICS Glass ceramic properties  FR 3.3 BIOACTIVE BIOCERAMICS Bioglass structure 3.3 BIOACTIVE BIOCERAMICS FR  FR Some typical room temperature properties of bioceramics and cortical/compact bone  Inert Ceramics (e.g., Non-Inert Ceramics (e.g., Bioactive Ceramics (e.g., FR Property Cortical Bone (Human) Alumina, Zirconia) Biodegradable ceramics) Hydroxyapatite, Bioglass) SUMMARY Minimal biological Can degrade or cause a Actively interact with body Biologically active, Interaction with Body interaction reaction over time tissues, promoting bonding remodeling capability Varies depending on High, promote bonding and High, naturally Biocompatibility High composition integration biocompatible Can undergo controlled Continuously remodeled by Degradation No degradation Degradable over time degradation the body 50-300 MPa (Biodegradable 50-150 MPa Tensile Strength 300-1000 MPa (Alumina) 50-150 MPa ceramics) (Hydroxyapatite) 100-500 MPa Compressive Strength 1000-3000 MPa (Zirconia) 50-200 MPa (Bioglass) 100-200 MPa (Biodegradable ceramics) 50-200 MPa (Biodegradable 50-150 MPa Flexural Strength 500-1500 MPa (Alumina) 50-150 MPa ceramics) (Hydroxyapatite) 0.1-1 MPa·m^0.5 Fracture Toughness 1-10 MPa·m^0.5 (Zirconia) 0.5-2 MPa·m^0.5 (Bioglass) 3-6 MPa·m^0.5 (Biodegradable ceramics) 200-400 GPa (Alumina, 10-50 GPa (Biodegradable Elastic Modulus 10-40 GPa (Hydroxyapatite) 5-20 GPa Zirconia) ceramics) Alumina: Used in joint Hydroxyapatite: Used in Tricalcium Phosphate (TCP): Human cortical bone: Examples replacements and dental bone grafts and tissue Used in temporary implants Structural support implants engineering Bioglass: Used in bone Zirconia: Used in dental Bioglass: Promotes bone Add a footer regeneration and dental 29 implants and prosthetics growth and bonding implants  FR GLOSSARY Property Definition Application The maximum stress a material can Important for materials under Tensile Strength withstand while being stretched or tension, such as cables, ropes, and pulled before breaking. some structural components. The maximum stress a material can Essential for load-bearing Compressive Strength withstand while being compressed applications, such as concrete, or squeezed before failing. bricks, and stone. The maximum stress a material can Relevant for materials subjected to withstand while being bent. Also Flexural Strength bending loads, such as beams, known as bending strength or slabs, and structural components. modulus of rupture. Critical for materials that need to A material's ability to resist crack withstand impact or high-stress Fracture Toughness propagation. Measures the energy environments, like aerospace required to grow a crack. components and safety-critical structures. Measures a material's stiffness, Important for understanding specifically the ratio of stress to material deformation under load, Elastic Modulus strain in the elastic deformation used in engineering and structural region. Also known as Young's analysis. modulus. Add a footer 30  4.0 BIODEGRADEDATION OF CERAMIC Add a footer 31 32 33 34  SIMULATED BODY FLUID BIOACTIVE TEST 35 4.0 BIODEGRADATION BIODEGRADATION OF CERAMIC ceramic degrade primarily via dissolution, this because ceramic formulation are highly soluble in aqueous environment Uncontrolled Controlled degradation degradation  FR 4.1 UNCONTROLLED DEGRADATION DEPEND ON TWO FACTOR 1. Mechanical environment Stress induced degradation can occur in ceramics under tension. If crack is formed in these materials, the tensile stress may lead to further dissolution at the crack tip and material fracture. 2. Ceramic porosity Pores are stress raiser thus may increase the formation of cracks or the rate of their propagation.  FR Uncontrolled degradation 4.1 UNCONTROLLED DEGRADATION Mechanical Ceramic porosity environment -stress raiser Uncontrolled degradation will cause Stress induced WEAR. degradation WEAR → the generation of fine wear particles that can lead to inflammation Wear and implant loosening. -main problem Produces biologically active particles Lead to inflammation and implant loosening  FR 4.1 CONTROLLED DEGRADATION Degradation is desirable. Controlled biomaterial degradation can be used as an important part of tissue engineering and drug delivery therapies. For these application, the temporary nature of the material is ideal to promote localized tissue healing or release of a bioactive agent without the need for second surgery to remove implant.  Introducing Nano-Hydroxyapatite.” (2016). Favorable Bioactivity of Porous Calcium Sulfate Scaffolds by Zhou, Jianhua et al. “Tunable Degradation Rate and CONTROLLED FR DEGRADATION Biodegradable ceramics are usually type of calcium phosphate, such as Hydroxyapatite, HA (Ca10(PO4)6(OH)2) Tricalcium phosphate, TCP (Ca3(PO4)2) Biodegradable ceramic generally degrade by dissolution (influenced by the solubility of the ceramic formulation in media and the pH of the media) coupled with physical disintegration. The bone scaffolds should possess suitable physicochemical properties and osteogenic activities. In this study, porous calcium sulfate (CaSO4) scaffolds were fabricated successfully via selected laser sintering (SLS). Nano-hydroxyapatite (nHAp), a bioactive material with a low degradation rate, was introduced into CaSO4 scaffolds to overcome the overquick absorption. The results demonstrated that nHAp could not only control the degradation rate of scaffolds by adjusting their content, but also improve the pH environment by alleviating the acidification progress during the degradation of CaSO4 scaffolds. Moreover, the improved scaffolds were covered completely with the apatite spherulites in simulated body fluid (SBF), showing their favorable bioactivity. In addition, the compression strength and fracture toughness were distinctly enhanced, which could be ascribed to large specific area of nHAp and the corresponding stress transfer  FR FACTOR THAT INFLUENCE DEGRADATION RATE 1. Amount of crystallinity Ceramic degradation depend on water penetration. A more tightly packed crystalline material is less susceptible to dissolution than a ceramic that is mainly amorphous (unstructured). Polycrystalline ceramics degrade more quickly than single crystal ceramic due to presence of grain boundaries. Ceramic contain many smaller crystals is more susceptible to dissolution than one with fewer, larger crystal. 6.2.1 FACTOR THAT INFLUENCE DEGRADATION RATE FR FR  FR FACTOR THAT INFLUENCE DEGRADATION RATE 2. Amount of media (water) available High amount of water → increase degradation rate Low amount of water → slower degradation rate 3. Material surface area to volume ratio Highly porous ceramic will dissolve more quickly than the same ceramic with fewer pores due to increase in area for interaction with the environment.  FR FACTOR THAT INFLUENCE DEGRADATION RATE 4. Mechanical environment Highly porosity Low porosity  FR FACTOR THAT INFLUENCE DEGRADATION RATE 4. Mechanical environment Ceramic degradation is encouraged in areas with high mechanical stress, either due to Implant site location Presence of stress raiser in the device Production of wear particles will caused inflammatory response → pH drop → accelerate degradation of material