This article presents the results of tests carried out on rapid quenched Fe-based alloys. The alloys were made using an injection-casting method. The actual structure of the alloys was also studied using an indirect method, based on H. Kronmüller's theorem. Based on analysis of the primary magnetization curves, in accordance with the aforementioned theory, it was found that Mo causes a change in internal regions associated with changes in the direction of the magnetization vector. The evolution of the thermal properties with increasing volume of Mo has been confirmed by the DSC curves. Addition of Mo, at the expense of the Nb component, results in changes to the crystallization process (i.e. the crystallization onset temperature and number of stages). The study showed that the addition of Mo at the expense of Nb reduces glass forming ability. Based on the DSC analysis, free volumes were determined for the alloys tested. These values were compared with the analysis of primary magnetization curves. It was found that the DSC curves can be used to indirectly describe the structure of amorphous alloys similar to the theory of the approach to ferromagnetic saturation. This approach is new and can be used by many researchers in this field.
Materials with so-called soft magnetic properties are an important object of material engineering research due to their potential application, among others, in the construction of low-loss transformer cores. Such properties are typical for alloys with an amorphous structure and with a high content of ferromagnetic elements: Fe, Co, Ni. Difficulties related with obtaining alloys which meet satisfactory dimensions result in the search for new solutions. One of them is the production of composites based on ferromagnetic powders obtained from amorphous alloys. This paper presents results of structure research for composite materials produced in a multi-stage production process. Magnetic composites were made on the basis of a bulk amorphous Fe70B20Y5Nb4Mo1 alloy produced by the injection method. On the basis of the obtained powder, two series of moldings were made: with 0.5% resin and covered with high-temperature varnish. Final composites were produced by using high temperature isostatic press. On the basis of the conducted research, it was found that the composites without resin are characterized by distinctly better magnetic properties as compared to resin-bonded composites.
The article presents the results of research on polymer composites based on polypropylene filled with various fillers. The physical and thermal properties of the composites are the result of the used polymer matrix as well as the properties and geometric features of the used filler. The geometric shape of the filler is particularly important in the processing of plastics in which the flow is forced, and high shearing tension occurs, which determines the high macromolecular orientation and specific arrangement of the filler particles. Thermal analysis (STA) was used in the research and photographs were taken using a scanning electron microscope (SEM) of fractures of polymer composites. The following fillers were used: talc, fibreglass, glass beads, and a halogen-free nitrogen-phosphorus flame retardant. The test material was obtained by extrusion. Shapes for strength tests, which were subjected to scanning microscopy tests after a static tensile test, were obtained by injection. The carried-out tests allowed us to determine the influence of the type and shape of individual fillers on structural changes in the structure of polypropylene composites and the degree of sample weight loss in a specific temperature range, depending on the used filler.
To fabricate a lead-free solder with better properties, a surface-modified precipitate calcium carbonate (PCC) was added as a reinforcement phase to tin-zinc (Sn-9Zn) solder. The surface modification of PCC was done by using electroless plating to deposit nickel (Ni) layer on the PCC. Based on microstructure analysis, a thin layer of Ni was detected on the reinforcement particle, indicating the Ni-coated PCC was successfully formed. Next, composite solder of Sn-9Zn-xNi-coated PCC (x = 0, 0.25, 0.50, 1.00 wt.%) was prepared. The morphology and phase changes of the composite solder were evaluated by using optical microscope and X-ray diffraction (XRD). Significant refinement on the grain size of Zn was seen with the additions of Ni-coated PCC, with a new phase of Ni3Sn4 was detected along with the phases of Sn and Zn. The wettability of Sn-9Zn was also improved with the presence of Ni-coated PCC, where the wetting angle decreased from 28.3° to 19.4-23.2°. Brinell hardness test revealed up to 27.9% increase in hardness for the composite solder than the pristine Sn-9Zn solder. This phenomenon contributed by the increased in dislocation resistance through Zener pinning effect and Zn grain refinement within the composite solder which enhanced the overall properties of the composite solder.
Zeolite has been successfully synthesized from clay and rice husk ash in the form of powder by using the hydrothermal method with variations in chemical compositions of alkaline solution and the amount of rice husk ash. The clay raw material was obtained from the Sidrap area of South Sulawesi and rice husk ash is obtained from the burning pile of rice husks. Sidrap clay and rice husk ash were activated using an alkaline solution of NaOH and varied rice husk ash and the addition of AlCl3. The addition of AlCl3, an alkaline solution of NaOH and H2O was used in the amount of 25.5 grams and variations of rice husk ash were 2.5 grams and 6.5 grams. Meanwhile, without the addition of AlCl3, an alkaline solution of NaOH and H2O was used for 20.5 grams and variations of rice husk ash from 2.5 grams and 6.5 grams. Then the mixture was then put into an autoclave with a temperature of 100°C for 3 hours. The basic material used in the manufacture of zeolite is carried out by X-ray Fluorescence (XRF) characterization to determine the constituent elements of basic material, which showed the content of SiO2 was 45.80 wt% in the clay and 93.40% in the rice husk ash. The crystalline structure of the zeolite formed was characterized by X-Ray Diffraction (XRD). It was found the resulting zeolite were identified as Zeolite-Y, Hydrosodalite, and ZSM-5. The microstructure properties of the resulting zeolite were determined by using Scanning Electron Microscopy (SEM).
Dramatic population and economic growth result in increasing demand for concrete infrastructure, which leads to an increment of freshwater demand and a reduction of freshwater resources. However, freshwater is a finite resource, which means that freshwater will be used up someday in the future when freshwater demand keeps increasing while freshwater resources are limited. Therefore, replacing freshwater with seawater in concrete blending seems potentially beneficial for maintaining the freshwater resources as well as advantageous alternatives to the construction work near the sea. There have been few experimental research on the effect of blending water salt content on the mechanical and physical characteristics of concrete, particularly high-strength concrete. Therefore, a research study on the influence of salt concentration of blending water on the physical and mechanical properties of high-strength concrete is necessary. This study covered the blending water salinity, which varied from 17.5 g/L to 52.5 g/L and was determined on the physical and mechanical properties, including workability, density, compressive strength, and flexural strength. The test results indicate that the use of sea salt in blending water had a slight negative influence on both the workability and the density of high strength concrete. It also indicates that the use of sea salt in blending water had a positive influence on both the compressive strength and the flexural strength of high-strength concrete in an earlystage.
TiO2 is one of the most widely used metal oxide semiconductors in the field of photocatalysis for the self-cleaning purpose to withdraw pollutants. Polyethylene glycol (PEG) is recommended as a stabilizer and booster during preparation of water-soluble TiO2. Preparation of SnO2/TiO2 thin film deposition on the surface of ceramic tile was carried out by the sol-gel spin coating method by adding different amount of PEG (0g, 0.2g, 0.4g, 0.6g, 0.8g) during the preparation of the sol precursor. The effects of PEG content and the annealing temperature on the phase composition, crystallite size and the hydrophilic properties of SnO2/TiO2 films were studied. The X-ray diffraction (XRD) spectra revealed different phases existed when the films were annealed at different annealing temperatures of 350°C, 550°C and 750°C with 0.4 g of PEG addition. The crystallite sizes of the films were measured using Scherrer equation. It shows crystallite size was dependent on crystal structure existed in the films. The films with mixed phases of brookite and rutile shows the smallest crystallite size. In order to measure the hydrophilicity properties of films, the water contact angles for each film with different content of PEG were measured. It can be observed that the water contact angle decreased with the increasing of the content of PEG. It shows the superhydrophilicity properties for the films with the 0.8 g of PEG annealed at 750°C. This demonstrates that the annealed temperature and the addition of PEG affect the phase composition and the hydrophilicity properties of the films.
The increasing needs of using aluminum epoxy composite as a replacement to solid metal rapid prototyping has opened to interests in optimizing its machining processes. This paper reported on the success of optimizing the surface roughness of aluminium epoxy composite using milling process along with a new finding on the best combination parameters. Taguchi method was used as the optimization method whereas spindle speed, feed rate, and depth of cut were set as input factors using an L9 Orthogonal Array. Analysis of Variance was used to identify the significant factors influencing the surface roughness. Experiment was conducted in dry condition using a vertical milling machine and the surface roughness after the machining was evaluated. Optimum combination of cutting parameters was identified after the finest surface roughness (response) based on the signal-to-noise ratio calculated. Cutting parameters selected after preliminary testing are cutting speeds of (2000, 3000 and 4000) rpm, feed rate (300, 400 and 500) mm/min, and cutting depth (0.15, 0.20, and 0.25) mm. The result showed that cutting speed had the largest percentage contribution to surface roughness with 69% and the second highest contribution was feed rate with 22% and depth of cut at 9%. The spindle speed was found as the most significant factor influencing the quality of surface roughness. The result is significant particularly in providing important guidelines for industries in selecting the right combination of parameters as well as to be cautious with the most significant factor affecting the milling process of metal epoxy composite.
In this globalized era, building materials play an essential role in the civil engineering field. Nowadays, with the increase in population, the demand for construction activities is also increasing. Polyethylene (PET) bottles are among the most widely used materials and cause an abundance of non-degradable waste, at about 0.94 million tonnes in Malaysia. One of the alternatives to reduce this waste's environmental impact is to incorporate it inside building materials such as brick and concrete. As PET bottles' recycling is highly promoted, the physical and mechanical properties of building materials made from PET bottles have also been reviewed. The data analysis shows that the compressive strength, flexural strength, split tensile strength and density of building materials decreases as the percentage of PET waste increases. However, other properties such as water absorption, initial absorption rate, and firing shrinkage increase proportionally with the PET waste. Besides, heavy metals in these building materials comply with the United States Environmental Protection Agency (USEPA) standards. It can be concluded that the percentage of PET waste incorporated into brick and concrete must be less than 5% and 2%, respectively, to produce suitable materials to provide alternatives in reducing and recycling PET waste.
Microstructures are an important link between materials processing and performance, and microstructure control is essential for any materials processing route where the microstructure plays a major role in determining the properties. In this work, silverdoped titanium dioxide (Ag/TiO2) thin film was prepared by the sol-gel method through the hydrolysis of titanium tetra-isopropoxide and silver nitrate solution. The sol was spin coated on ITO glass substrate to get uniform film followed by annealing process for 2 hours. The obtained films were annealed at different annealing temperatures in the range of 300°C-600°C in order to observe the effect on crystalline state, microstructures and optical properties of Ag/TiO2 thin film. The thin films were characterized by X-Ray diffraction (XRD), scanning electron microscopy (SEM), and UV-Vis spectrophotometry. It is clearly seen, when the annealing temperature increases to 500°C, a peak at 2θ = 25.30° can be seen which refers to the structure of TiO2 tetragonal anatase. The structure of Ag/TiO2 thin film become denser, linked together, porous and uniformly distributed on the surface and displays the highest cut-off wavelength value which is 396 nm with the lowest band gap value, which is 3.10 eV.
Filler surface modification has become an essential approach to improve the compatibility problem between natural fillers and polymer matrices. However, there is limited work that concerns on this particular effect under dynamic loading conditions. Therefore, in this study, both untreated and treated low linear density polyethylene/rice husk composites were tested under static (0.001 s-1, 0.01 s-1 and 0.1 s-1) and dynamic loading rates (650 s-1, 900 s-1 and 1100 s-1) using universal testing machine and split Hopkinson pressure bar equipment, respectively. Rice husk filler was modified using silane coupling agents at four different concentrations (1, 3, 5 and 7% weight percentage of silane) at room temperature. This surface modification was experimentally proven by Fourier transform infrared and Field emission scanning electron microscopy. Results show that strength properties, stiffness properties and yield behaviour of treated composites were higher than untreated composites. Among the treated composites, the 5% silane weight percentage composite shows the optimum mechanical properties. Besides, the rate of sensitivity of both untreated and treated composites also shows great dependency on strain rate sensitivity with increasing strain rate. On the other hand, the thermal activation volume shows contrary trend. For fracture surface analysis, the results show that the treated LLDPE/RH composites experienced less permanent deformation as compared to untreated LLDPE/RH composites. Besides, at dynamic loading, the fracture surface analysis of the treated composites showed good attachment between RH and LLDPE.
Fe-based bulk metallic glasses (BMGs) have been extensively investigated due to their ultrahigh strength and elastic moduli as well as desire magnetic properties. However, these BMGs have few applications in industrial productions because of their brittleness at room temperature. This study is focused on the effect of cooling rate on the mechanical properties (especially toughness) in the Fe41Co7Cr15Mo14Y2C15B6 BMG. For this aim, two samples with the mentioned composition were fabricated in a water-cooled copper mold with a diameter of 2 mm, and in a graphite mold with a diameter of 3 mm. The formation of crystalline phases of Fe23(B,C)6, α-Fe and Mo3Co3C based on XRD patterns was observed after the partial crystallization process. To determine the toughness of the as-cast and annealed samples, the indentation technique was used. These results revealed that the maximum hardness and toughness were depicted in the sample casted in the water-cooled copper mold and annealed up to 928°C. The reason of it can be attributed to the formation of crystalline clusters in the amorphous matrix of the samples casted in the graphite mold, so that this decrease in the cooling rate causes to changing the chemical composition of the amorphous matrix.
The composition and structural modification of aluminium alloys influence their strength, tribological properties and structural stability. The phase composition of the structure as well as the characteristics of the elementary cell of each identified phase was established by X-ray diffraction, and the main objective was to determine the compositional phases, microstructure and microcomposition of the alloy. Based on the cyclic voltammograms it can be said that on the OCP interval (+1.5 V… -1.1 V), after the breakthrough potential is an intensification of the anodic process by the pronounced increase of the current density, in these conditions the Al-Si alloy has low values which means that it has a better corrosion resistance.
This study compares the mechanical properties of recycled high-density polyethylene (r-HDPE)/rice husk (RH) composites from a twin-screw extruder and a heated two-roll mill, and the effect of different filler loadings using different melt blending processes on the mechanical properties of r-HDPE/RH composites. Polyethylene-graft-maleic anhydride (MAPE) acts as the coupling agent to enhance interfacial bonding between the fibre and the polymer matrix. The filler loading used was in the range of 10-40 wt. %. In this work, r-HDPE/RH blends were prepared using a twin-screw extruder and a heated two-roll mill. The ratio of 70/30 twin-screw extruder compounded composites significantly showed higher tensile based on improved to about 45.5% at 11 MPa compared to those compounded in the heated two-roll mill. The same ratio showed an increment almost up to 9% of elongation at break. It has also been verified that the higher filler loading used reduced the tensile strength and elongation at break, while the Young’s modulus increased. The result was evidenced by the increase in water absorption and longer burning time as the filler loading increased.
The disposal of industrial steel mill sludge in landfills has frequently received significant concern as the sludge has a very notable potential to contaminate soil surface and groundwater in the long run. Recently, the incorporation of industrial steel mill sludge into fired clay brick has become one of the promising alternative methods as it could produce a lightweight product while minimizing the environmental impact of the waste used. In this study, fired clay bricks as the most common building material were incorporated with 0%, 5%, 10% and 15% of steel mill sludge and fired at 1050°C (heating rate of 1°C/min). The manufactured bricks were subjected to physical and mechanical properties such as firing shrinkage, dry density, and compressive strength while the Toxicity Characteristic Leaching Procedure (TCLP) was conducted to analyze leaching behavior from the manufactured bricks. The results demonstrated that incorporation up to 15% of steel mill sludge reduces the properties up to 27.3% of firing shrinkage, 8.1% of dry density and 67.3% of compressive strength. The leaching behavior of Zn and Cu from steel mill sludge was reduced up to 100% from 7414 to 9.22 ppm (Zn) and 16436 to 4.654 ppm (Cu) after 15% of sludge incorporation. It was observed that high temperature during the firing process would improve the properties of bricks while immobilizing the heavy metals from the waste. Therefore, recycling steel mill sludge into construction building materials could not only alleviate the disposal problems but also promote alternative new raw materials in building industries.
Stone mastic asphalt is a gap-graded mix and is usually related to its high bitumen content and its skeleton-like constitution. Although famous for its durability, high resistance to fatigue and rutting, issues such as bleeding and premature aging do occur in the mix since it has a high bitumen content and voids due to its gap-graded structure. In order to encounter these problems from affecting the mix, some instances such as adding additives, rejuvenators and stabilizers into the mixture has been implemented. Nowadays, nano materials are being used in the asphalt mixtures and nano titanium is being introduced as a modifier to the asphalt binder in order to improve the mechanical properties of the stone mastic asphalt mix. The related tests done in order to access the improvement are resilient modulus, dynamic creep, moisture susceptibility and binder drain down. The content of nano titanium used in this research are 1%, 2%, 3%, 4% and 5%. This study is done to assess the mechanical performance of stone mastic asphalt with nano titanium modified binder.
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