1. UKM Learning and Research Repository
2. PHD Thesis / Tesis PHD
3. Faculty of Engineering and Built Environment / Fakulti Kejuruteraan dan Alam Bina

Title:	Powder injection moulding of titanium alloy irregular shape-hydroxyapatite as implant material
Authors:	Nurul Nadiah Mahmud (P93131)
Supervisor:	Abu Bakar Sulong, Prof. Ir. Dr.
Keywords:	Universiti Kebangsaan Malaysia -- Dissertations Dissertations, Academic -- Malaysia Powder injection moulding Titanium alloy Implant material
Issue Date:	1-May-2022
Description:	Powder Injection Moulding (PIM) shows the potential in producing geometrical and complex shaped metal and ceramic products with lower cost. Irregular powder is not widely used in PIM due to it has lower packing density and particle flowability in comparison to spherical powder particle. This research focused on potential usage of irregular powder particles, which commonly have lower manufacturing process cost than spherical shape as an alternative in PIM industry. The fabrication of titanium alloyhydroxyapatite (Ti6Al4V-HA) composites are gaining attention these years for their potential usage as implant materials. Therefore, main objective of this study is to investigate the processability of irregular-shaped Ti6Al4V-HA composite through the PIM process, simultaneously to determine potential usage of irregular-shaped Ti6Al4VHA composite as implant material. This research focused on rheological properties, powder loading, flowability, physical and mechanical properties of sintered parts, and the biocompatibility of Ti6Al4V-HA composite. Ti6Al4V and HA powder with density of 4.35 and 3.13 g/cm3, respectively, were used as main materials in this research. Ti6Al4V-HA composite powder at powder ratio 90:10 wt. % was tested for critical powder volume percentage (CPVP). Binder composition of 60 wt. % palm stearin and 40 wt. % of polyethylene of feedstocks were used for Ti6Al4V-HA composite powder at different powder loading. The injection moulding process were carried out at injection temperature of 170 °C, mould temperature of 70 °C, injection pressure of 15 bar, and holding time of 2 seconds. Solvent debinding was carried out by immersion in heptane solution for 6 hours at 60 °C to remove palm stearin at early stage. Subsequently, thermal debinding was carried out at 500 °C in an environment of argon gas for 3 hours to remove polyethylene. The sintering temperature was done at 1300 °C, and with presintering step at 900 °C in vacuum atmophere, where the heating rate was maintained at 3 °C/min. CPVP value was obtained at 68 vol.%. Based on CPVP value, Ti6Al4V-HA composite feedstock were produced at four different powder loading of 63, 64, 65 and 66 vol.%. The rheological results on all powder loading showed pseudoplastic flow behaviour, where viscosity increases as the shear rate decreases. The density of Ti6Al4V-HA composite of sintered part were obtained between 3.5 ° 0.4 and 3.8 ° 0.4 g/cm3, which is between density of Ti6Al4V and HA. SEM images of showed sintered parts with porous structure is beneficial for implantation. The bending strength of the sintered parts was between 67.8 ° 10.4 and 81.6 ° 6.4 MPa (60 until 130 MPa bone strength), while Young's modulus was between 9.8 ° 2.3 and 11.6 ° 1.5 GPa (10 until 30 GPa Young's modulus of bone). XRD analysis showed pre-sintering restrained the decomposition of HA. The biocompatibility properties of sintered Ti6Al4V-HA composite were obtained through biocompatibility tests using PrestoBlue™ solution. The absorbance value increased as the immersion days increased. This has proven that the Ti6Al4V-HA composite was non-toxic and biocompatible. Based on the results obtained, it has proven that irregular-shaped Ti6Al4V-HA feedstock demonstrated properties similar with spherical-shaped Ti6Al4V-HA in term of rheological behaviour was successfully produced through PIM and have the potential to be used as implant material. The potential usage of irregular powder in PIM helps in reducing the total cost production due to its low price of raw materials.,Ph.D.
Pages:	196
Publisher:	UKM, Bangi
Appears in Collections:	Faculty of Engineering and Built Environment / Fakulti Kejuruteraan dan Alam Bina

Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.