Effects of debinding and sintering atmosphere on properties and corrosion resistance of powder injection molded 316 L - stainless steel

316L stainless steel is a common biomedical material. Currently, biomedical parts are produced through powder injection molding (PIM). Carbon control is the most critical in PIM. Improper debinding can significantly change the properties of the final product. In this work, thermal debinding and sintering were performed in two different furnaces (i.e. laboratory and commercially available furnaces) to study the mechanical properties and corrosion resistance. Debounded samples were sintered in different atmospheres. The samples sintered in inert gas showed enhanced mechanical properties compared with wrought 316L stainless steel and higher corrosion rate than those sintered in the vacuum furnace. The densification and tensile strength of the hydrogen sintered samples increased up to 3% and 51%, respectively, compared with those of the vacuum-sintered samples. However, the samples sintered in inert gas also exhibited reduced ductility and corrosion resistance. This finding is attributed to the presence of residual carbon in debonded samples during debinding

SMVS: A Web-based application for graphical visualization of malay text corpus

Information visualization is an interesting field nowadays. A good information visualization ensures distraction of misleading information is not included in the visualization. Many studies have been conducted on the Quranic corpus. The advancement technology coupled with modern approach of the computer technology can support the learners to understand Qur'an easily. Smart Malay Visualization System (SMVS) is a Python Flask framework web application which help users efficiently to produce the most basic data visualization from a big data. This web application displayed information from the state-of-the-art corpus which is identified through text. Agile development has been adapted to prepare this web application. Six phases of the methodology have been implemented in this study which are requirements, analysis, planning, design, implementation, testing, and deployment. Natural Language Processing approach has been used to visualize the data. Twenty most informative word from each verse has been visualized using Frequency Distribution and has been embedded to the web application. This work focuses on the Malay translation of the Qur'an corpus

Robotic exoskeleton control for lower limb rehabilitation of knee joint

Wearable devices such as exoskeletons are being opted frequently during rehabilitation processes for the post stroke recovery. Such de-vices are playing important role in the development of assistive rehabilitation robotic systems. In this paper three control strategies MPC and LQR and PID are introduced which were applied to knee joint of lower limb exoskeleton model for passive exercise. The two con-trols MPC and LQR are model based control which empowers them for stable responses. In this paper the analysis of robustness of con-trol is done under the noisy and disturbance conditions. The results showed good performance of the exoskeleton model with the applied controls in the provided condition. In the future work the applied controls will be implemented on hardware

Effect Of Sintering Temperature On Density, Hardness And Tool Wear For Alumina-Zirconia Cutting Tool

Combination of alumina (Al 2 O 3 ) and zirconia (ZrO 2 ) as cutting tool have been established themselves as a dominant in ceramic category for dry machining. The mechanical properties of Al 2 O 3 -ZrO 2 cutting tool were critically dependent on its density and hardness, which affected by the powder preparation and sintering processes. This paper present the effect of sintering temperature on density, hardness and tool wear of Al 2 O 3 -ZrO 2 cutting tool. Specific composition of 80-90 wt% Al 2 O 3 and 10-20 wt% ZrO 2 powders were mixed and ball milled for 12 hours. These powders then were compacted in the form of RNGN120600 designated cutting tool by using manual hydraulic press before undergone secondary compaction by Cold Isostatic Press. The compacted powders then were sintered from 1200°C to 1400°C at constant 9 hours soaking time. For each sintered cutting tool, evaluation has been made based on the density and hardness. By using AISI 1045 as a workpiece material, the wear performance of the selected cutting tools were evaluated within 200-350 m/min cutting speeds, 0.1 mm/rev feed rate and 0.5 mm depth of cut. The results shows that the sintering temperature at 1400°C and 9 hours soaking time produced maximum relative density and hardness for 90 wt% Al 2 O 3 and 10 wt% ZrO 2 at 94.17% and 63.4 HRC respectively. Cutting tool contained with 80 wt% Al 2 O 3 and 20 wt% ZrO 2 contributed maximum relative density of 97% and hardness of 70.07 HRC. Maximum tool life recorded was 156s at 200 m/min cutting speed. Wear mechanisms of fabricated cutting tool dominated by the notch and flank wear at the early stage of machining and formation built up edge at the end of machining process

Provision of spaces and space quality in housing area towards quality of life: case study of Taman Melati Mastika, Gombak

Every successful housing space is fix upon its user satisfaction living in that space itself. The quality of house and the spaces within the unit can be said as the most compelling factors in scaling the user satisfaction in dwelling in the residential area that can lead to a better quality of life. Limitation of space following high land cost that affect the indoor and outdoor spaces needs to be studied as it affects the residents’ satisfaction. Hence, this study concentrates on spaces within a housing area and their quality, as well as the opinion of the residents and their level of satisfaction and space utilization.The focus of the study is on double-storey terraced houses because it is among the most common and dominant form of housing in Malaysia. The techniques employed in collecting data are observation and survey questionnaire with the respondent rate of 25.2%. This study provides an insight on the types of outdoor spaces (front yard-front lane and backyard-back lane) and their elements and utilization, indoor spaces utilization, and quality of housing spaces toward users’ quality of life in Taman Melati Mastika, Kuala Lumpur. The result of this study suggests that the residents are satisfied with the existing spaces within their compound and adjacent to it, and this lead towards the overall satisfaction living in the area. It can also be said that quality spaces and good utilization of housing spaces can lead towards a better quality of life in the terrace housing area

Fabrication And Machining Performance Of Ceramic Cutting Tool Based On The Al2O3-ZrO2-Cr2O3 Compositions

This study presents the cutting tool development of zirconia toughened alumina (ZTA) with chromia addition. The process used for its development is solid-state, in which the powders of Alumina (Al2O3), Zirconia (ZrO2) and Chromia (Cr2O3) were processed by a ball mill, compacted under a Cold Isostatic Press (CIP) and sintered at a constant temperature of 1400 °C with 9 h soaking time. The initial study investigated the effect of Polyethylene glycol (PEG) as a binder, CIP and hardness of Al2O3-ZrO2 mixtures. The percentage composition between Al2O3 and ZrO2 was varied to choose the best for the highest mechanical performances determined by the density, porosity and properties analysis. The cutting tool that possessed the highest hardness and bending strength was selected the Al2O3-ZrO2 mixture was mixed 0.6 wt% Cr2O3 for machining trials within the cutting speed of 200-350 m/min and constant feed rate and depth of cut of 0.150 mm/rev and 0.5 mm, respectively. The results of the ZTA mixed with Cr2O3 and combined with the ratio 80-20-0.6 wt% showed that the addition of 0.6 wt% PEG and a CIP pressure at 300 MPa and 60 s dwell time resulted maximum hardness and bending strength of 71.03 HRc and 856.02 MPa, respectively. The fabricated cutting tool was capable to reach 225 s tool life when machining AISI 1045 at a lower cutting speed of 200 m/min and higher feed rate of 0.150 mm/rev

A critical review of the effects of fluid dynamics on graphene growth in atmospheric pressure chemical vapor deposition

Chemical vapor deposition (CVD) of graphene has attracted high interest in the electronics industry due to its potential scalability for large-scale production. However, producing a homogeneous thin-film graphene with minimal defects remains a challenge. Studies of processing parameters, such as gas precursors, flow rates, pressures, temperatures, and substrate types, focus on improving the chemical aspect of the deposition. Despite the many reports on such parameters, studies on fluid dynamic aspects also need to be considered since they are crucial factors in scaling up the system for homogenous deposition. Once the deposition kinetics is thoroughly understood, the next vital step is fluid dynamics optimization to design a large-scale system that could deliver the gas uniformly and ensure maximum deposition rate with the desired property. In this review, the influence of fluid dynamics in graphene CVD process was highlighted. The basics and importance of CVD fluid dynamics was introduced. It is understood that the fluid dynamics of gases can be controlled in two ways: via reactor modification and gas composition. This paper begins first with discussions on horizontal tubular reactor modifications. This is followed by mechanical properties of the reactant gasses especially in terms of dimensionless Reynolds number which provides information on gas flow regime for graphene CVD process at atmospheric pressure. Data from the previous literature provide the Reynolds number for various gas compositions and its relation to graphene quality. It has been revealed that hydrogen has a major influence on the fluid dynamic conditions within the CVD, hence affecting the quality of the graphene produced. Focusing on atmospheric pressure CVD, suggestions for up-scaling into larger CVD reactors while maintaining similar fluid properties were also provided

Effect Of Hydraulic Pressure On Hardness, Density, Tool Wear And Surface Roughness In The Fabrication Of Alumina Based Cutting Tool

Cutting tools can be considered major industrial necessities as it applied mostly to machine components. Development of self-fabricated cutting tool can facilitate lower machining cost as long as the cutting tool can perform effectively. This paper presents the effect of hydraulic pressure on density, hardness, wear performance and surface roughness during fabrication of the alumina based ceramic cutting tool. Specific raw of alumina powders were ball milled compacted into green body using hydraulic press with different pressures of 6, 7, 8 and 9 tons. These green bodies were sintered at 1700°C in 4 hours soaking time. Hardness and density of sintered bodies were examined in order to correlate the effect of hydraulic pressure on mechanical properties. The samples were further tested into machining with AISI 1045 in order to evaluate their wear performances and surface roughness. The results show that density and hardness increased as the hydraulic pressure increased. The highest pressure of 9 tons demonstrated highest density and hardness of 2.77 g/cm3 and 86.1 HRA respectively. The fabricated cutting tool capable to cut the AISI 1045 steel with the minimum wear rate recorded at 0.0025 mm/s for 9 ton of pressured sample. In terms of failure modes, the cutting tool suffered with abrasive wear and cracks at the edge of tool nose radius. Surface roughness demonstrate minimum 1.24 μm for 7 ton of pressure, which considered high for short time machining process. Overall, the self-fabricated cutting tool capable to cut the steel without catastrophic failure which demonstrated promising results to be improved in the future

The role of gas-phase dynamics in interfacial phenomena during few-layer graphene growth through atmospheric pressure chemical vapour deposition

The complicated chemical vapour deposition (CVD) is currently the most viable method of producing graphene. Most studies have extensively focused on chemical aspects either through experiments or computational studies. However, gas-phase dynamics in CVD reportedly plays an important role in improving graphene quality. Given that mass transport is the rate-limiting step for graphene deposition in atmospheric-pressure CVD (APCVD), the interfacial phenomena at the gas–solid interface (i.e., the boundary layer) are a crucial controlling factor. Accordingly, only by understanding and controlling the boundary-layer thickness can uniform full-coverage graphene deposition be achieved. In this study, a simplified computational fluid dynamics analysis of APCVD was performed to investigate gas-phase dynamics during deposition. Boundary-layer thickness was also estimated through the development of a customised homogeneous gas model. Interfacial phenomena, particularly the boundary layer and mass transport within it, were studied. The effects of Reynolds number on these factors were explored and compared with experimentally obtained results of the characterised graphene deposit. We then discussed and elucidated the important relation of fluid dynamics to graphene growth through APCVD

HYDROLOGICAL PERFORMANCE OF NATIVE PLANT SPECIES WITHIN EXTENSIVE GREEN ROOF SYSTEM IN MALAYSIA

ABSTRACT Little is known about the hydrological performances of different native plant species within extensive green roof system in Malaysia. Thus, this research focused on the runoff retention efficiency within extensive green roof system with respect to different native plant species in Malaysia. A total of six green roofs were constructed with five being vegetated and one left unvegetated. Four test beds were vegetated with Nephrolepis bisserata (fern), Axonopus compressus (cow grass), portulaca grandiflora cultivars (sedum) and Zoysia matrella (Manila grass). The fifth test bed was a combination of all species and the six test bed with bare soil acted as control. The runoff volume was measured volumetrically through connected to an surface runoff harvesting tank under the test beds. Water retention was calculated from the difference between the depth of rainfall and the depth of runoff from each test bed. Results showed that mixture of plant species was the most effective vegetation at reducing runoff water. The monoculture of portulaca grandiflora cultivars (sedum) performed the best runoff water retention efficiency for single plant species