Effect of Sintering Temperature Rate on Physical Properties of Porous Tricalcium Phosphate (TCP) Ceramics

Transcription

1 Effect of Sintering Temperature Rate on Physical Properties of Porous Tricalcium Phosphate (TCP) Ceramics Ahmad Fadli 1, Abdul Rasyid 1 *, Ricky Firmansyah 1 1 Jln. HR. Subrantas Km. 12,5. Department of Chemical Engineering, Faculty of Engineering, Riau University. Pekanbaru, Riau Indonesia * abdulrasyid8793@gmail.com Abstract. Porous Tricalcium Phosphate (TCP) were designed for the use in bone implant via starch-consolidation method and the effect of sintering temperature rate was investigated. TCP suspension were mixed with wheat particles then stirred for 1 hour. The slurries were cast into cylindrical shaped molds and then dried for consolidation process at 100 C for 30 minutes, 80 C for 24 hours and 120 C for 8 hours. Afterward, the dried bodies were burned at 350 C for 1 hour and continued at 600 C for 1 hour, then followed by sintering at 1100 C with termperature rate of 2, 5, 8 C/minute for 1 hour. The sintered TCP bodies with shrinkage in the range 56-59% and porosity in range 61-82% were obtained. Increasing sintering temperature rate from 2 to 5 C/minute will reduce compressive strength from 0.73 to 2.89 MPa. INTRODUCTION The bones are defined as connective tissue and their function as a structural component of the human body are well known, serves to support, protect delicate parts and organs and provides a connection between the muscles, allowing movement [1]. Bone defect will disturb their functions and it must be repaired. The biomaterials were used to restore the function of traumatized or degenerated connective tissues and thus Improve the quality of life of a patient [2]. Synthetically produced calcium phosphate ceramics and implants have an important position among other biomaterials because they are considered to be almost fully biocompatible with living body when replacing the hard bone tissues [3]. Implantation of bone by using bone grafts is known strategies for treatment of large bone defects which all lead to limited degree of structural and functional recovery. However, limited supply, donor site morbidity and risk of transmission of pathological organisms impose major limits to their widespread use [4]. Tricalcium Phosphate (TCP) are bone substitute materials that are marked out by their high biocompatibility, favourable resorption properties and osteoconductivity [3]. Calcium hydroxyapatite (Ca 3 (PO 4 ) 6 (OH) 2 (HA)) and tricalcium phosphate (Ca 3 (PO 4 ) 2 (TCP)) are currently recognized as ceramics materials that significantly simulate the mineralogical structure of bone [5]. Porous calcium phosphate ceramics have found enormous use in biomedical applications including bone tissue regeneration, cell proliferation, and drug delivery [6].

2 EXPERIMENTAL The materials in this research were Tricalcium phosphate powder, Wheat particles, Aquadest, HNO 3 and Castor oil. Tricalcium phosphate (Merck, German) was used as the bioactive material. Wheat particles (PT. Indofood Sukses Makmur Tbk, Indonesia) was used as porous agent. Aquadest (Merck, Germany) were used as solvent. HNO 3 (Merck, Germany) were used for set slurry ph at 3.5. Castor oil was used as the lubricant for facilitating demolding. The slurries were prepared by mixing TCP and aquadest in a beaker glass. Then wheat particles and HNO 3 were added to the slurries. The slurries were mechanically stirred at 200 rpm for 1 hour. Subsequently, the slurries were cast in cylindrical open stainless steel mould with mm diameter and mm height and dried in an oven at 100 C for 30 minutes then continued at 80 C for 24 hours and 120 C for 8 hours. Afterward, the dried bodies were burned at 350 C for 1 hour and continued at 600 C for 1 hour, then followed by sintering at 1100 C with termperature rate of 2, 5, 8 C/minute for 1 hour. Scheme of research procedure and mechanism of temperature gain were shown in Figure 1 and Figure 2. Composition of slurries and sintering temperatures rate studied are as listed in Table 1. TCP Aquadest Mixing Wheat Stirring HNO 3 Molding Drying Demolding Burning Sintering Characterization Porous TCP

3 FIGURE 1. Scheme of research procedure T ( C) hour 2, 5, 8 C/minute hour 2 C/minute 1 hour 2 C/minute Time FIGURE 2. Mechanism of temperature gain in burning and sintering Slurry TABLE 1. Slurry composition and sintering temperature studied TCP (g) Wheat (g) Water (ml) Sintering Temperature Rate ( C/Minute) S S S RESULTS AND DISCUSSION To investigate effect of sintering temperature on the physical properties of porous TCP, samples S1, S2 and S3 were evaluated. Measurement of shrinkage, density, porosity and compressive strength of all samples are presented in Table 2. TABLE 2. Effect of sintering temperature rate on physical properties Slurry Shrinkage Density Porosity Compressive Strength (% Volume) (g/cm 3 ) (%) ( C/Minute) S S S Samples were sintered at 1100 C with sintering temperature rate 2, 5, 8 C/minutes. When the sintering temperature rate increased from 2 to 8 C/minute, the shrinkage of porous TCP decreased from to 35.87%. Shrinkage decreases as sintering temperature rate increases. Lower sintering temperature rate enhanced samples densification rate, and at the same time the grain growth increases. Table 2 shown the samples porosity at range 60-75%. Decreases on sintering temperature rate caused the porosity decreased, at the same time it explain the structure of samples were more compact and the density of

4 samples were increased. When the sintering temperature rate increased from 2 to 8 C/minute, the density of TCP were decreased from 1.23 to 0.8 g/cm 3, this increases caused by the particles become compact and the densification was occurred. Table 2 also reveals that the compressive strength of porous TCP was decreased while the sintering temperature rate increased from 2 to 8 C/minutes. The compressive strength of porous TCP was in range MPa. The compressive strength of porous ceramics increased as the porosity deacreased. a) b) c) FIGURE 3. Microstucture of bodies after sintered with temperature rate a) 2 C/minute b) 5 C/minute c) 8 C/minute The microstructure of samples changed obviously with the increasing sintering temperature rate. Figure 3 shows the sintering temperature rate increases caused the increases on porous size and fused into larger grains. Figure 3 also explain the changed of particles distance. The particle get spaced while the temperature rate increase. Figure 3c show that the porous size of sample S3 was bigger than sample S1 and S2. That indicated TCP had opened porous with good interconnectivity.

5 A B C TCP HA FIGURE 4. XRD pattern of porous TCP bodies after sitered with temperature rate a) 2 C/minute b) 5 C/minute c) 8 C/minute Figure 4 shows the changes on sintering temperature rate should not have any effect on chemical structure of samples. That because samples were sintered at same temperature (1100 C), meanwhile the sintering temperature rate (2, 5, 8 C/minute) was used as variable in this research. The chemical structure of samples were effected by sintering temperature [7]. CONCLUSIONS Porous TCP were successfully manufactured via starch-cosolidation technique using wheat particles as porous agent. The porosity of sintered porous TCP obtained by this method was % and the compressive strength was MPa. When the sintering temperature rate increased from 2 to 8 C/minute, the shrinkage of porous TCP decreased from to 35.87%. the changed on sintering temperature rate should not have any effect on chemical structure of porous TCP.

6 ACKNOWNLEDGEMENT The authors are thankful to the Ministry of National Education, Republic of Indonesia (DIKTI) for funding this research. REFERENCES [1] -. Hydroxyapatite-Based Materials: Synthesis and Characterization, Biomedical Engineering - Frontiers and Challenges, Prof. Reza Fazel (Ed.), ISBN: , InTech, Available from: (2011). [2] Park, S. H., Llinás A., Goel, V. K. & Keller, J. C. Hard tissue replacement. The Biomedical Engineering Handbook: Second Edition. Ed. Joseph D. Bronzino. Boca Raton: CRC Press LLC. (2000). [3] Ain, R.N., I. Sopyan, and S. Ramesh. Preparation of Biphasic Calcium Phosphate Ceramics Powders and Conversion to Porous Bodies. ICCBT Proceedings. (2008). [4] Saki, M., Narbat, M.K., Samadikuchaksaraei, A., Ghafouri, H.B. and F. Gorjipour,. Biocompability study of a hydroxyapatite-alumina and silicon carbide composite scaffold for bone tissue engineering. Yakhteh Med. J. 11(1): (2009). [5] Kivrak, N. and Cuneyt, A.T., Synthetis of Calcium Hidroxyapatite-Tricalcium Phosphate (HA-TCP) Composite BioceramicsPowders and Their Sintering Behavior. J. Am. Ceram. Soc. 81 [9] (1998). [6] Abdurrahim, T. & Sopyan, I. Recent progress on the development of porous bioactive calcium phosphate for biomedical applications. Biomed. Eng. 1: (2008). [7] Kang, S-J., L. Sintering: densification, grain growth and microstructure. Amsterdam: John Wiley & Sons. (2005).