Papers by Keyword: Density

Abstract: Pervious concrete, or "porous concrete," is characterized by its sand-free mixture. Therefore, it is classified as a type of lightweight concrete. Due to the trend towards using sustainable materials to preserve the environment by getting rid of waste and reducing carbon dioxide production, four mixtures were prepared in this research. The first mixture was used to control the mixture. Second, 30 % of the volume of coarse aggregate was replaced with brick waste aggregate. After that, 10% of the Cement was replaced by metakaoline. Finally, carbon fibre was added by 1% of the weight of the Cement. Compressive strength, Density, and flexural strength tests were conducted. The results of the tests demonstrated that the previous concrete mixture, including 30% crushed brick, 10% metakaolin, and 1% carbon fibres, had greater compressive strength at 7 and 28 days of curing than a mix containing 30% brick waste. The Density of pervious concrete, which contains waste, decreased compared to that of the original concrete. Adding carbon fibres led to a slight improvement in compressive strength and a good improvement in the flexural and splitting tests compared with the mixture containing brick waste and Metakaolin.

Abstract: Ballistics is the science and dynamics of a moving projectile. This field helps to understand the accuracy of different projectiles, from bullets to rockets. Ballistics is based on physics, particularly Newtonian mechanics, and plays an important role in the defense industry, as well as space exploration, sports, and many other areas of life. The study of ballistics is broadly divided into four distinct segments: internal, transitional, external, and terminal ballistics. Each segment provides insight into a particular stage in the projectile's life.External ballistics plays an important role in the study of the movement process of the bullet during its movement, in understanding and optimizing the principle of operation of firearms, artillery and other ballistic systems. Understanding external ballistics is critical in firearms, artillery, archery, and even sports such as golf and baseball. In this article, we will delve into the ins and outs of external ballistics and explore the various factors that affect projectile range.

Abstract: Ceramic Metallic Alloys of TiC/Ni, Comprising Titanium Carbide with Nickel Contents of 5%, 15%, 30%, and 50%, were Fabricated through Solid-Phase Sintering at 1400°C with a 2-hour Holding Time and a Pressure of 50MPa. This Study Explores the Impact of Nickel Content on the Mechanical and Structural Properties. The Solidification Mechanism between TiC and Ni is Governed by Carbon Diffusion through TiC Particles, Affecting the Morphology of TiC and Carbon Particles in Ni Samples. The Reaction Behavior within the TiC/Ni Alloys was Analyzed, and Microstructural and Mechanical Characteristics were Examined to Evaluate the Influence of Varying Nickel Contents. Results indicate that in all samples, the TiC matrix exhibited a solid solution of the FCC phase. The reaction mechanism of Ti-C-Ni reveals the evolution of solid phase formation with increasing nickel content. As nickel content increases, the mass and size of nickel particles grow, leading to a more uniform and homogeneous structure. At a nickel content of 15%, the samples displayed a bending strength of 1200 ± 50 N, a microhardness of 800 ± 20 (HV _0.1), and a density of 5.6 ± 0.2.

Abstract: This research aims to review the physical properties of Lightweight Cellular Concrete (CLC) bricks with the addition of Labuhan Batu Selatan red sand. CLC bricks have the advantage of being lightweight and larger in size, which can expedite the construction process. CLC bricks are made by adding air bubbles/foaming agents to the mortar mix as an expander to produce lightweight bricks with a lower material composition. It is crucial for the air bubbles to maintain their shape during the mortar curing process without causing any chemical reactions. In this study, lightweight bricks were made by experimenting with various combinations of red sand and river sand, with variations of 0% red sand and 100% red sand, using the Cellular Lightweight Concrete (CLC) method. The research method employed was experimental, testing the physical properties of CLC lightweight bricks, specifically density and compressive strength, in accordance with the SNI 03-6825-2002 standard. As a result, with the addition of red sand in the production of CLC lightweight bricks, the density falls within the lightweight brick category, but it does not significantly improve the compressive strength of the lightweight bricks. This is because the CaCO3 (calcium carbonate) content in the CLC lightweight brick mix has the highest intensity, causing the bricks to become brittle. Therefore, this research suggests paying more attention to the mixing and blending processes of the materials to achieve a more uniform distribution.

Abstract: This research investigated metal injection moulding of dental pins for orthodontics application. 316L stainless steel powder was selected as an alternative low-cost material in comparison to the more expensive titanium alloy counterpart. The feedstock was prepared at 60% solid loading using an environmentally friendly multi-component binder. Injection moulding was operated using a four-cavity mould. The effects of moulding temperature of 250-280 °C measured at the barrel on mouldability, and specimen properties were studied. After debinding, specimens were sintered at 1250 °C for 2 hours in a hydrogen atmosphere. Experimental results indicated that injection at moulding lower temperature of 250-260 °C gave better mouldability, providing less specimen distortion and demoulding difficulty. The green density was 5.49 g/cm³, giving 93.41% theoretical density. Injection at lower temperature of 250-260 °C also provided higher sintered density and slightly lower volume shrinkage. Sintered microstructure experienced densification with small degree of isolated porosity in specimen center, however with interconnected porosity along specimen edges, responsible for 6.87 g/cm³ sintered density (86.01% theoretical density).

Abstract: The utilization of nickel aluminide compounds in high-temperature structural applications is advantageous due to their desirable properties. One efficient method for producing nickel aluminide samples with desirable chemical reactions using minimal energy is reactive sintering. In this study, Ni-Al (20 wt.%-80 wt.%) compounds were fabricated by initially cold pressing them, followed by reactive sintering. The reactive sintering process resulted in the formation of NiAl₃ and Ni₂Al₃ phases within the Ni-Al compounds. The microstructure, porosity, and hardness of the samples were thoroughly examined and analyzed. Generally, the compounds produced through reactive sintering exhibited significant porosity attributed to shrinkage and the Kirkendall effect. Microstructural analysis confirmed the presence of porosity, NiAl₃, and Ni₂Al₃ phases. The sintered sample processed at 400 °C demonstrated higher density and hardness. Additionally, the wear test indicated a low wear rate and friction coefficient for the sintered sample processed at 400 °C.

Abstract: Additive manufacturing is one of the emerging domains in the industry. The ability to build complex and accurate metallic prototypes is crucial in the verifying the design of many essential components. Direct metal laser sintering technique is a type of laser powder bed fusion methods that is used to print samples with good accuracy. Typically, Al alloys are used in these techniques, mainly due to their high mass to strength ratio and good corrosion resistance. These alloys are typically used in the automobile and aero-space industry. This research focus on the effects of DMLS technique on the density and hardness of the sample

Abstract: The density of green compact in powder metallurgy (PM) is a critical characteristic to determine the strength and tenacity of the product. Due to the fragility and sensitivity to the humidity of green compact, detection method triggers by knocking or immersion cannot be applied. Current inspection method for green compact is to use a densitometer with Archimedes Principle, which has to immerse green compact into water. This action considers a destructive test due to the porosity of the PM product, and the oxidation reaction of metal particles inside products cannot be controlled. Since the current detection method is destructive, most of the inspection on forming process of PM only complies after setup of compaction machine. The next non-destructive test is executed after sintering, such as Acoustic emission testing (AE) and Magnetic Testing (MT), which require a solid object for knocking or liquid immersion. To reduce defective compaction flow into the manufacturing process, a Non-destructive test in forming process is a prerequisite. Laser Doppler Vibrometer (LDV) takes advantage of measuring without damaging the test object and obtaining characteristic spectrum signal from the sample for further analysis, which is preferable for green compact of PM. The LDV test setup included a Polytec PSV-400 scanning laser vibrometer with a crystal resonator attached to the test product to generate reference vibration. Integrate spectrum in the frequency range 0 - 5000 Hz was recorded from 30 points of an annular pattern. Comparison of the spectrum and statistical analysis from defective specimens demonstrate that velocity increases within a specific frequency, which is different from with normal samples. Increases in velocity refer to uneven density distribution with an absence of particles inside product decline. The study approves the possibility of density detection in green compact using an LDV. Further studies aim to construct a relational model of specimen and compaction machine and determine a fundamental database for Advance Process Control (APC) of forming process in PM.

Abstract: Direct ink writing (DIW) is an extrusion additive manufacturing (AM) technique in which inks are extruded through a nozzle and then deposited layer-by-layer. This technology allows 3D printing many different materials such as ceramics, metals, food, etc. In this work, the performance of zirconia pastes is addressed. The pastes are composed of yttria stabilized zirconia (YSZ) powder and a polymeric binder. Ceramic content is a mix of two components: A and B. Both the total content of ceramic and the content of component A in the paste are varied, according to a 3² design of experiments. The paste was characterized regarding Densification (%) and Elastic modulus G’ (Pa). A new parameter w³/G’ is defined to evaluate the viscosity of the inks. In the tests, the ceramic percentage is limited by the pressing force of the plunger that will be used to extrude the pastes. On the other hand, the binder concentration is also limited, because it requires to be in a gel form in order to be properly extruded. The results showed that Densification depends mainly on ceramic content, while the w³/G’ parameter is related to percentage of component A. In this work, the properties of the pastes prior to 3D printing are assessed. However, in the future, the pastes will be used to extrude complex parts with medical applications. AM extrusion processes constitute a possible way to overcome the difficulties to obtain complex geometries with conventional methods such as machining, in which zirconia parts can break due to their brittleness. Thus, the results of this work will help to manufacture complex shapes with porous areas in zirconia, when the DIW technology is employed.

Abstract: The article presents the physical, mechanical (strength, density), and chemicalcharacteristics of complex M100 water-resistant mortar compositions, which include crushedlimestone (0.16–1.25 mm) and granite-crushed sand. Additionally, stone masonry mortar mixtureswith a grain size of up to 5 mm have been developed using local raw materials for the restoration ofwall constructions in building structures.The relationship between the density and chemical stabilityof the hardened samples was determined using the results of complex research on the structuringprocess of the test samples obtained with the modifiers used to improve the workability of theprocessed lime mortars.