CHUI KIM NG - Academia.edu (original) (raw)
Papers by CHUI KIM NG
Chemical Engineering & Technology
Hydroxyapatite (HA) was synthesized from chicken bone waste by calcination. Pectin was extracted ... more Hydroxyapatite (HA) was synthesized from chicken bone waste by calcination. Pectin was extracted from orange peels by microwave irradiation, and 1 and 3 wt % of pectin was incorporated into the HA. The resulting powders were then pressed into disk samples before being sintered at temperatures of 1050, 1150, and 1250 °C for 2 h. Various analytical techniques, including Fourier transform infrared spectroscopy, X‐ray diffraction, scanning electron microscopy, density measurement, and Vickers microhardness tests, were used to evaluate the characteristics and mechanical properties of the samples. The incorporation of pectin did not interfere with the pure phases of HA, and minimal amounts of β‐tricalcium phosphate were detected in the XRD patterns. Both ball milling and the addition of pectin effectively reduced the particle size of HA. However, the addition of pectin above 1 wt % did not contribute significantly to the densification and hardness of chicken bone‐derived HA (CHA) compared...
IIUM Engineering Journal
Hydroxyapatite (HA) is a type of calcium phosphate-based bioactive ceramic that resembles the min... more Hydroxyapatite (HA) is a type of calcium phosphate-based bioactive ceramic that resembles the mineral phase of bone and teeth with great potential for bone substitution and biomedical implants. Biogenic-derived HA emerges as a cheap and eco-sustainable alternative to improve waste utilization. However, hydroxyapatite has limited applications due to its apparent brittleness, thus prompting investigation for enhanced sintering properties. In the present study, the combination of calcination and chemical precipitation technique was used to extract hydroxyapatite (HA) from ark clamshells (Anadara granosa). The method successfully produced HA powder with a Ca/P ratio of 1.6 and characteristic bands corresponded to pure HA via Fourier Transform Infrared Spectroscopy (FTIR). The synthesized HA powder was then sintered at temperatures ranging from 1200 °C to 1300 °C, followed by mechanical evaluation of the density, Vickers hardness, fracture toughness and grain size. It was revealed that ...
Oxide ion conductors have important applications in oxygen sensors, pumps and SOFCs. The best-kno... more Oxide ion conductors have important applications in oxygen sensors, pumps and SOFCs. The best-known oxide ion conductor is stabilized zirconia with exclusive ionic conductivity at elevated temperature. An understanding of the impact from the use of dopant on the zirconia ceramic is critical for tailoring the fabrication and high temperature operational stability of these devices. The conventional sintering method is time and energy consuming, in contrast to traditional approaches to heat transfer based on radiation and convection, rapid microwave heating allows volumetric heating, thus a potential alternative sintering route to provide accelerated densification with limited grain growth. This research work investigated the effect of manganese oxide (MnO 2) dopant and sintering on the properties of ceria-doped scandia stabilized zirconia (10Sc1CeSZ). Commercially available 10Sc1CeSZ ceramic powder was compared with the powder synthesized via solid state sonication-ball milling method. The results showed that all 10Sc1CeSZ sintered compacts prepared from commercial powder had pure cubic phase, with better resulting mechanical and electrical performance compared to synthesized powder. The effect of MnO 2 additions on the properties of 10Sc1CeSZ was investigated and the results showed that the addition up to 1 wt% had negligible effect on the mechanical properties of the ceramic. The samples containing up to 1 wt% MnO 2 attained above 97.5 % relative density, Vickers hardness of 13-14 GPa and fracture toughness of 3 MPam 1/2. In addition, it was revealed that the 0.5 wt% MnO 2 addition was beneficial in suppressing the cubic zirconia grain growth i.e. the highest average grain size was measured at 4.9 µm when sintered at 1550 C as compared to 9.9 µm measured for the undoped zirconia when sintered at the same temperature. On the other hand, the addition of 5 wt% MnO 2 was found to be detrimental to the densification and
Applied Science and Engineering Progress, 2020
With outstanding integration of mechanical performances and biocompatibility, 3 mol% of yttria st... more With outstanding integration of mechanical performances and biocompatibility, 3 mol% of yttria stabilised tetragonal zirconia polycrystals (3Y-TZP) ceramic are extensively fabricated as biomedical implants. Conventional sintering (CS) was generally employed to produce 3Y-TZP bodies with promising densification, which resulted in grain coarsening and mechanical properties deterioration due to elevated sintering temperatures (> 1500°C). The main weakness of 3Y-TZP ceramic is the spontaneous tetragonal to monoclinic phase transformation under humid environment, which is known as low-temperature degradation (LTD). In present work, undoped and MnO 2 (0.3 and 0.5 wt%) doped 3Y-TZP green bodies were prepared and subjected to CS at 1200-1500°C for an hour of dwelling time. It was found that the optimum concentration of MnO 2 dopant was 0.5 wt%. Reasonable toughness values of 5-7 MPa.m 1/2 revealed the tetragonal phase stability of 3Y-TZP grains was not altered by doping of MnO 2. Moreover, outstanding density level of > 96% of 0.5 wt% MnO 2 doped 3Y-TZP ceramics demonstrated the superb Young's modulus of > 200 GPa and Vicker's hardness of >13 GPa. Fabrication of 3Y-TZP by doping MnO 2 had reduced the total processing time by ~ 9% and sintering temperature by up to 150°C when compared to undoped 3Y-TZP ceramics sintered at 1400°C.
Advanced Materials Research, 2014
This project investigated the use of facile pulping methods to produce pulp from mixed bio-planta... more This project investigated the use of facile pulping methods to produce pulp from mixed bio-plantation waste fibres using sodium hydroxide, ethanol and garbage enzyme. Papers were successfully made from mixture of corn husk fibres with other bio-based green fibres such as banana stems and pineapple leaves. Soda pulping was found to be efficient in converting the cellulosic bio-fibres to the pulps used for paper making. The papers produced have low tensile strength, high water absorption, high bio-decomposition and degradation rate, as compared to commercial papers. SEM observation revealed that paper made from mixed bio-fibres have lightly cross-linked structures compared to heavily cross-linked or compact network structures found in commercial papers. The paper can be used in applications that require high water absorbency. The paper making process is more environmental friendly as it reduces the usage of wood fibres and hence reduces the environmental problem caused by deforestation.
Sodium silicate has been widely used in the foundry as a binder to make sand moulds and cores. Ho... more Sodium silicate has been widely used in the foundry as a binder to make sand moulds and cores. However, the collapsibility of the sodium silicate bonded sand is normally low for sand reclamation. In this study, the effect of composition alteration of sodium silicate mixing with water as the binder for sand molding to improve the collapsibility of the cast iron casting sand was investigated. The sand specimens were prepared using 4 to 6 weight % of binder. The strength of the sand specimens and their collapsibility were examined. The size and shape of the sand grains produced from the reclamation were also studied. It is observed that sand moulds made with 6 weight % binder with 4:1 (sodium silicate to water) ratio has the sufficient compression strength to hold the sand particles together and a low retained compressive strength that increases the collapsibility of the sand mould.
Chemical Engineering & Technology
Hydroxyapatite (HA) was synthesized from chicken bone waste by calcination. Pectin was extracted ... more Hydroxyapatite (HA) was synthesized from chicken bone waste by calcination. Pectin was extracted from orange peels by microwave irradiation, and 1 and 3 wt % of pectin was incorporated into the HA. The resulting powders were then pressed into disk samples before being sintered at temperatures of 1050, 1150, and 1250 °C for 2 h. Various analytical techniques, including Fourier transform infrared spectroscopy, X‐ray diffraction, scanning electron microscopy, density measurement, and Vickers microhardness tests, were used to evaluate the characteristics and mechanical properties of the samples. The incorporation of pectin did not interfere with the pure phases of HA, and minimal amounts of β‐tricalcium phosphate were detected in the XRD patterns. Both ball milling and the addition of pectin effectively reduced the particle size of HA. However, the addition of pectin above 1 wt % did not contribute significantly to the densification and hardness of chicken bone‐derived HA (CHA) compared...
IIUM Engineering Journal
Hydroxyapatite (HA) is a type of calcium phosphate-based bioactive ceramic that resembles the min... more Hydroxyapatite (HA) is a type of calcium phosphate-based bioactive ceramic that resembles the mineral phase of bone and teeth with great potential for bone substitution and biomedical implants. Biogenic-derived HA emerges as a cheap and eco-sustainable alternative to improve waste utilization. However, hydroxyapatite has limited applications due to its apparent brittleness, thus prompting investigation for enhanced sintering properties. In the present study, the combination of calcination and chemical precipitation technique was used to extract hydroxyapatite (HA) from ark clamshells (Anadara granosa). The method successfully produced HA powder with a Ca/P ratio of 1.6 and characteristic bands corresponded to pure HA via Fourier Transform Infrared Spectroscopy (FTIR). The synthesized HA powder was then sintered at temperatures ranging from 1200 °C to 1300 °C, followed by mechanical evaluation of the density, Vickers hardness, fracture toughness and grain size. It was revealed that ...
Oxide ion conductors have important applications in oxygen sensors, pumps and SOFCs. The best-kno... more Oxide ion conductors have important applications in oxygen sensors, pumps and SOFCs. The best-known oxide ion conductor is stabilized zirconia with exclusive ionic conductivity at elevated temperature. An understanding of the impact from the use of dopant on the zirconia ceramic is critical for tailoring the fabrication and high temperature operational stability of these devices. The conventional sintering method is time and energy consuming, in contrast to traditional approaches to heat transfer based on radiation and convection, rapid microwave heating allows volumetric heating, thus a potential alternative sintering route to provide accelerated densification with limited grain growth. This research work investigated the effect of manganese oxide (MnO 2) dopant and sintering on the properties of ceria-doped scandia stabilized zirconia (10Sc1CeSZ). Commercially available 10Sc1CeSZ ceramic powder was compared with the powder synthesized via solid state sonication-ball milling method. The results showed that all 10Sc1CeSZ sintered compacts prepared from commercial powder had pure cubic phase, with better resulting mechanical and electrical performance compared to synthesized powder. The effect of MnO 2 additions on the properties of 10Sc1CeSZ was investigated and the results showed that the addition up to 1 wt% had negligible effect on the mechanical properties of the ceramic. The samples containing up to 1 wt% MnO 2 attained above 97.5 % relative density, Vickers hardness of 13-14 GPa and fracture toughness of 3 MPam 1/2. In addition, it was revealed that the 0.5 wt% MnO 2 addition was beneficial in suppressing the cubic zirconia grain growth i.e. the highest average grain size was measured at 4.9 µm when sintered at 1550 C as compared to 9.9 µm measured for the undoped zirconia when sintered at the same temperature. On the other hand, the addition of 5 wt% MnO 2 was found to be detrimental to the densification and
Applied Science and Engineering Progress, 2020
With outstanding integration of mechanical performances and biocompatibility, 3 mol% of yttria st... more With outstanding integration of mechanical performances and biocompatibility, 3 mol% of yttria stabilised tetragonal zirconia polycrystals (3Y-TZP) ceramic are extensively fabricated as biomedical implants. Conventional sintering (CS) was generally employed to produce 3Y-TZP bodies with promising densification, which resulted in grain coarsening and mechanical properties deterioration due to elevated sintering temperatures (> 1500°C). The main weakness of 3Y-TZP ceramic is the spontaneous tetragonal to monoclinic phase transformation under humid environment, which is known as low-temperature degradation (LTD). In present work, undoped and MnO 2 (0.3 and 0.5 wt%) doped 3Y-TZP green bodies were prepared and subjected to CS at 1200-1500°C for an hour of dwelling time. It was found that the optimum concentration of MnO 2 dopant was 0.5 wt%. Reasonable toughness values of 5-7 MPa.m 1/2 revealed the tetragonal phase stability of 3Y-TZP grains was not altered by doping of MnO 2. Moreover, outstanding density level of > 96% of 0.5 wt% MnO 2 doped 3Y-TZP ceramics demonstrated the superb Young's modulus of > 200 GPa and Vicker's hardness of >13 GPa. Fabrication of 3Y-TZP by doping MnO 2 had reduced the total processing time by ~ 9% and sintering temperature by up to 150°C when compared to undoped 3Y-TZP ceramics sintered at 1400°C.
Advanced Materials Research, 2014
This project investigated the use of facile pulping methods to produce pulp from mixed bio-planta... more This project investigated the use of facile pulping methods to produce pulp from mixed bio-plantation waste fibres using sodium hydroxide, ethanol and garbage enzyme. Papers were successfully made from mixture of corn husk fibres with other bio-based green fibres such as banana stems and pineapple leaves. Soda pulping was found to be efficient in converting the cellulosic bio-fibres to the pulps used for paper making. The papers produced have low tensile strength, high water absorption, high bio-decomposition and degradation rate, as compared to commercial papers. SEM observation revealed that paper made from mixed bio-fibres have lightly cross-linked structures compared to heavily cross-linked or compact network structures found in commercial papers. The paper can be used in applications that require high water absorbency. The paper making process is more environmental friendly as it reduces the usage of wood fibres and hence reduces the environmental problem caused by deforestation.
Sodium silicate has been widely used in the foundry as a binder to make sand moulds and cores. Ho... more Sodium silicate has been widely used in the foundry as a binder to make sand moulds and cores. However, the collapsibility of the sodium silicate bonded sand is normally low for sand reclamation. In this study, the effect of composition alteration of sodium silicate mixing with water as the binder for sand molding to improve the collapsibility of the cast iron casting sand was investigated. The sand specimens were prepared using 4 to 6 weight % of binder. The strength of the sand specimens and their collapsibility were examined. The size and shape of the sand grains produced from the reclamation were also studied. It is observed that sand moulds made with 6 weight % binder with 4:1 (sodium silicate to water) ratio has the sufficient compression strength to hold the sand particles together and a low retained compressive strength that increases the collapsibility of the sand mould.