Department of Chemical Engineering, Riau University, Pekanbaru, Indonesia.

Transcription

1 Journal of Materials Science and Chemical Engineering, 2016, *, ** Published Online **** 2016 in SciRes. Effect of Sintering Temperature on Microstructure and Properties of Porous β-tricalcium Phosphate Scaffolds Prepared By Using Protein Foaming-Consolidation Method Abdul Rasyid*, Ahmad Fadli, Fajril Akbar Department of Chemical Engineering, Riau University, Pekanbaru, Indonesia. Received **** 2016 Copyright 2016 by author(s) and Scientific Research Publishing Inc. This work is licensed under the Creative Commons Attribution International License (CC BY). Abstract Tricalcium phosphate (TCP) is bioceramics which has good biocompatibility properties and does not cause inflammation when used as a bone tissue implant. Porous β-tcp scaffold were prepared by using protein foaming-consolidation method and the effect of temperature sintering was investigated. β-tcp powder, egg yolk, sago powder and Darvan 821A were mechanical stirred at 150 rpm for 3 hours. Then, the slurries were casted in a cylindrical stainless stell mold and heated at 180 C for 1 hour. Subsequently, dried samples were demolded and burned at 600 C for 1 hour. For the final steps, samples were sintered at 1000 and 1100 C for 1 hour. The compressive strength of porous bodies obtained from this research was MPa with % porosity and density in range of g/cm 3. Keywords Tricalcium Phosphate, Protein Foaming-Consolidation, Porous Ceramic 1. Introduction Tricalcium phosphate (TCP) is a biocompatible ceramics whose physical and chemical properties similar to the mineral structure of human bone and teeth. TCP are bone substitute materials that are marked out by their high biocompatibility, favourable resorption properties and osteoconductivity [1]. TCP has been widely used in the repair of bone and metal coatings in tissue replacement. Porous β-tcp scaffold were prepared by using protein foaming-consolidation method. It was a technique for production of porous tricalcium phosphate (TCP) using How to cite this paper: Rasyid, A., Fadli, A. and Akbar, F. (2016) Effect of Sintering Temperature on Microstructure and Properties of β-tricalcium Phosphate Scaffold Prepared By Using Protein Foaming Consolidation Method. *********, *, **-**.

2 egg yolk as pore creating agent. Egg yolk is a complex association of water, lipids and proteins. The lipids phase in egg yolk would reduce the foaming capacity of protein in making pores [2]. 2. Experimental β-tricalcium Phosphate Powder (Sigma Aldrich, German) were used as the bioactive materials. Protein used was yolk that freshly isolated from chicken egg (Yuki Farm, Indonesia). Palm oil (Multimas Nabati Asahan, Indonesia) was used as the lubricant for facilitating demolding. Sago flour was used as the binder. Darvan 821 A (R.T. Vanderbilt, USA) was selected as the dispersant agent. 24 gr β-tcp powder, 24 gr egg yolk, 3 gr sago powder and 6 gr Darvan 821A were mechanical stirred at 150 rpm for 3 hours. Then, the slurries were casted in a cylindrical stainless stell mold and heated at 180 C for 1 hour. Subsequently, dried samples were demolded and burned at 600 C for 1 hour. For the final steps, samples were sintered at 1000 and 1100 C for 1 hour. The theoretical densities of fully densified tricalcium phosphate, 3.14 gr/cm 3 is used as the reference to calculate total volume fraction of porosity. The mechanical strength of sintered porous β-tcp was measured using a universal testing machine. The crystallinity of sintered porous β-tcp was analyzed by XRD (PANalytical, X Pert 3 Powder). The microstructure of porous β-tcp was examined using SEM (JEOL, 5600 Model). 3. Results and Discussion To determine the effect of sintering temperature on porous β-tcp, samples was sintered at 1000 and 1100 C. After sintering process, samples were performed without significant deformation which indicated good homogeneity of the materials. Figure 1 shows sintered porous β-tcp in cylindrical shape. 1 cm 1 cm Figure 1. Porous β-tcp after sintered at 1000 C and 1100 C While drying process, the slurry encounter the foaming-consolidation process. Foaming of slurry took place in four steps: pre-heating of slurry without increasing volume, foaming stage with the strongly increased until reaches a maximal value, consolidating stage with the volume of drying body is reaching minimum and then undergoes a plateau (stabilizing stage) [2]. The evolution of foaming capacity versus the drying time of slurry is shown in Fig. 2. The pre-heating stage take place at 2 min drying tim, the foaming stage at 2-18 min drying time and consolidation stage at min drying time. The stability of foam was achieved after the body dried more than 20 min [3]. In this study the physical properties measured were the percentage of shrinkage, porosity and density. The shrinkage occured as the yolk was removed, which were initially packed loosely, approached and contacted. The removal of yolk left holes in the walls. The holes were the source of voids that probably moved from the centre to the outer surface during sintering, and at the same time the particles moved toward the internal surface of bodies. These movements led to the shrinkage of bodies, and the shrinkage is more intensive with the increasing sintering temperature [4]. Increasing temperatures will increase the rate of densification of the sample so that the particles become dense ceramic, it make the volume of bodies get smaller and instead increase the shrinkage of bodies. The shringkage of bodies was increased from 16.38% to 40.37%. 2

3 Volume Increase (v/v) A. Rasyid, A. Fadli, F. Akbar Drying Time (min) Figure 2. Increasing volume during drying process Increasing the sintering temperature also causes the decreasing porosity that occurs in the sample. With increasing sintering temperature, the rate of densification to be increased, this resulted formed pores will be closed so that the porosity of the samples will be reduced. After sintering at 1000 C the porosity of bodies was 64.82% and it reduced to 53.22% while the bodies sintered at 1100 C. Density of porous bodies will increase with decreasing porosity. Porosity stated the number of void space on the bodies, the less amount of void space on bodies would make the bodies become more dense. By increasing the sintering temperature, the density of the sample will increase, this increase is due to the particle be compact and solidified (densification) at high temperature. Increasing in density of porous bodies will increase the compressive strength of bodies. In the process of sintering the structure of the material particles will grow (coarsening) and fused to form a unity mass (densification). The rate of densification will increase if the temperature gets higher, the greater the pressure, the smaller the particle size and the longer the sintering time [4]. The influence of sintering temperature on density and compressive strength are presented at Table 1. Table 1. Effect of sintering temperature on shrinkage, density, porosity and compressive strength Sintering Temperatur Shringkage (%) Porosity (%) Density (g/cm 3 ) Compressive Strength (MPa) 1000 C C In the sintering process, there are several variables that can affect the microstructure of the material, such as temperature, pressure, time, and the rate of sintering [4]. In this research, the samples were sintered at 1000 C and 1100 C with rate of sintering was 2 C/min.. Lower sintering temperature rate enhanced samples densification rate, and caused the porosity decreased, at the same time it explain the structure of samples were more compact and the density of samples were increased [5]. 3

4 TCP Figure 3. XRD Pattern of Porous β-tcp after sintering at 1000 C and 1100 C Figure 3 shows that by raising the sintering temperature will change the chemical structure of the material. This change is shown by the diffraction peak which indicates the crystal of TCP. By raising the sintering temperature, the translational symmetry of a crystal is lost. When part of the translational symmetry of a crystal is lost and the rotational motions become relatively fast, the crystal reaches the liquid crystalline state [6]. While the crystal transform into the liquid crystalline state, the intensity of β-tcp diffraction peak will decreased. 10/29/2015 2:08:24 PM HV kv Mag o Spot x 7.0 det tilt ETD 0 10 µm 10 µm 10 µm UNIVERSITY STATE OF MALANG 10/29/2015 2:28:54 PM HV kv Mag o Spot x 7.0 det tilt ETD 0 10 µm UNIVERSITY STATE OF MALANG Figure 4. Microstructure of Porous β-tcp after sintering at 1000 C and 1100 C Microstructure of porous ceramics will also change due to an increase in the sintering temperature. At high 4

5 temperatures, the chemical structure of polycrystalline solid will become unstable, resulting in the occurrence of boundary migration followed by the boundary diffusion [4]. This causes the surface of the grains will stick and bind to one another. Figure 5 shows by the sintering temperature increases, the number of grains bonded to one another will increase. 4. Comclusions We have investigated the effect of Sintering Temperature on Microstructure and Properties of Porous β-tricalcium Phosphate Scaffolds Prepared By Using Protein Foaming-Consolidation Method. Increasing sintering temperatures cause decreased porosity, increased density, and greater compressive strength. XRD results show that crystallinity of porous bodies decreased with the increasing sintering temperatures. By the sintering temperature increases, the number of grains bonded to one another will increase. Acknowledgements The authors are thankful to the Ministry of National Education, Republic of Indonesia (DIKTI) for funding this research under Student Creativity Program (PKM). References [1] Ain, R.N., I. Sopyan, and S. Ramesh. (2008) Preparation of Biphasic Calcium Phosphate Ceramics Powders and Conversion to Porous Bodies. ICCBT Proceedings. [2] Fadli, A. and Sopyan, I. (2009). Preparation of Porous Alumina for Biomedical Applications through Protein Foaming-Consolidation Method. Material Research Innovation. 13(3): [3] Fadli, A. and Sopyan, I. (2011). Porous ceramics with controllable properties prepared by protein foaming-consolidation method. Journal of Porous Materials. 18: [4] Kang, S-J., L. (2005). Sintering: densification, grain growth and microstructure. Amsterdam: John Wiley & Sons. [5] Fadli, A., Rasyid, A. & Firmansyah, R. (2014). Effect of Sintering Temperature Rate on Physical Properties of Porous Tricalcium Phosphate (TCP) Ceramics. Proceeding ASEAN COSAT Bogor [6] Katritzky, A.R., Jain, R., Lomaka, A., Petrukhin, R., Maran, U. and Kalerson, M. (2001). Perspective on the Relationship between Melting Points and Chemical Structure. Crystal Growth & Design. 4: