Numerical Investigation of Iron Ore Tailings Filled Epoxy Composite as Heat Resistant Material

The thermal properties of epoxy composites reinforced with iron ore tailings were used to investigate the thermal performance of the composite as heat resistant material. Thermal properties are important parameters for determining the behaviour and appropriate applications of materials. This paper focuses on investigating the thermal performance of epoxy composite reinforced with iron ore tailings (IOT) of particles sizes 150 µm, 10% reinforced. The thermal properties of the selected epoxy-IOT composite were specific heat capacity – 2352 J/kg-K, thermal resistivity – 4.788 °C-m/W, thermal diffusivity – 0.089 mm2/s and Thermal conductivity – 0.209 W/m-K. The selected epoxy-IOT composite was numerically compared with an existing material (gypsum board) of the following thermal properties: specific heat capacity – 1090 J/kg-K, thermal resistivity – 3.87°C-m/W, thermal diffusivity – 0.333 mm2/s and Thermal conductivity – 0.258 W/m-K. The numerical analysis was done using Autodesk Fusion360, by modelling the materials as slabs.The heat transfer process of the composite and the prediction of the heat resistance capability were explained by comparing the results with an existing material (gypsum plasterboard) using their mechanical and thermal properties.The numerical results indicated that the epoxy-IOT composite has lower minimum temperature and thermal stress compared with the existing material (gypsum board), which implies that epoxy-IOT composite when used as a heat insulator will resist heat and sustain thermal stress better than the gypsum board of the same geometry under the same conditions. In conclusion, an epoxy-IOT composite of appropriate mixing ratio and geometry can be comfortable use as heat resistant materials. Keywords— Epoxy-IOT, Numerical Analysis, Temperature Distribution, Thermal Performance, Thermal Stress

Influence of Supraglacial Debris Thickness on Thermal Resistance of the Glaciers of Chandra Basin, Western Himalaya

A large number of glaciers in the Hindu-Kush Himalaya are covered with debris in the lower part of the ablation zone, which is continuously expanding due to enhanced glacier mass loss. The supraglacial debris transported over the melting glacier surface acts as an insulating barrier between the ice and atmospheric conditions and has a strong influence on the spatial distribution of surface ice melt. We conducted in-situ field measurements of point-wise ablation rate, supraglacial debris thickness, and debris temperature to examine the thermal resistivity of the debris pack and its influence on ablation over three glaciers (Bara Shigri, Batal, and Kunzam) in Chandra Basin of Western Himalaya during 2016–2017. Satellite-based supraglacial debris cover assessment shows an overall debris covered area of 15% for Chandra basin. The field data revealed that the debris thickness varied between 0.5 and 326 cm, following a spatially distributed pattern in the Chandra basin. The studied glaciers have up to 90% debris cover within the ablation area, and together represent ∼33.5% of the total debris-covered area in the basin. The supraglacial debris surface temperature and near-surface air temperature shows a significant correlation (r = > 0.88, p = < 0.05), which reflects the effective control of energy balance over the debris surface. The thermal resistivity measurements revealed low resistance (0.009 ± 0.01 m2°C W−1) under thin debris pack and high resistance (0.55 ± 0.09 m2°C W−1) under thick debris. Our study revealed that the increased thickness of supraglacial debris significantly retards the glacier ablation due to its high thermal resistivity.

Production injection moulds with additive technology by the HP MJF 4200 printer

This paper is focused on the production plastic parts. It is describing two technologies-injection moulding and additive technology. The production process of the metal mould for the new parts takes about ten weeks. It is necessary to make some reductions after the mould is produced. It is increasing the time which is necessary for the prototype of products. This time (from the initial design of mould to the prototype of product) can take about six months. Additive technologies can be used for decreasing this time and for cost reduction. Moulds produced by the additive technology are mostly special inserts which can be implemented in the universal design of mould. It is also possible to produce whole moulds from plastic material. These moulds can have integrated cooling channels. There are high demands on the material of the mould with respect to the thermal resistivity, toughness and surface quality. There are really often used SLA technologies, which are considering the High Temp Resin and Material Jetting Digital ABS. Other options used in the factories are Somos PerFORM and Digital ABS Plus. This paper deals with the possibility of usage of the HP Jet Fusion technology with the material PA12 GB for the production of mould inserts and it is evaluating this process and repeatability of process.

Investigation of the Thermo-Physical and Mechanical Properties of Coir and Sugarcane Bagasse for Low Temperature Insulation

This research reports on the suitability of Agricultural bi-products as low temperature thermal insulating materials to replace synthetic insulating materials like polyurethane used in food warmers and ice coolers. Coir and sugarcane bagasse chosen for this research was based on literature review and local availability of materials. Coir was obtained from Badagry, Lagos State and Sugarcane bagasse obtained from Batati, Niger State, the materials were washed, sun dried for three days and cut into smaller pieces before being blended into smaller particles using an electric blender. The blended materials (Coir and Bagasse) were sieved into two different sieve size of 0.5 mm and 1.0 mm respectively. The particles sizes were then combined into blend ratios of 50/50, 60/40, and 70/30 using Gum Arabic as binder. Thermal conductivity test showed that 1.0 mm particle size coir mixed with sugarcane bagasse has the lowest thermal conductivity of 0.01467 W/mK whilst that of 0.5 mm particle size has thermal conductivity of 0.01472 W/mK this is lower compared to the measured thermal conductivity of the polyurethane control sample of 0.01832 W/mK. Sample F (1.0 mm particle size,70% coir and 30% bagasse) with a thermal diffusivity of 5.15 m²/s, water absorption capacity of 410 %, UTS of 0.219 MPa, Compressive strength of 0.583 MPa, Specific heat capacity of 1141.3 J/kgK and thermal resistivity of 68.16 W/m/K is most suitable replacement for polyurethane as low temperature thermal insulator. This is corroborated by the performance evaluation test with carried out between polyurethane lined food warmer and bio-composite lined food warmer. The two test samples have close ice melt rate values and the polyurethane slightly edge the Bio-composite insulating material by 1.2 % in efficiency. The edge in efficiency can be accepted as all materials used in the development of the bio-composite insulating material are completely bio-degradable and environmentally friendly.

Experimental Investigations and Microstructural Characterization of Construction Materials of Historic Multi-Leaf Stone-Masonry Walls

In order to correctly define the pathology of multiple-leaf stonemasonry walls and determine the appropriate interventions for its conservation and preservation, comprehensive studies on its building materials should be carried out since the overall behaviour of masonry structures is highly dependent on the characterization of its construction materials. Consequently, an interdisciplinary procedure for construction material characterization used in multiple-leaf stone-masonry walls in Egypt has been implemented to enrich documentation, conservation and restoration issues of this type of wall. The research methodology integrates experimental data obtained through on-site sampling, conducted tests and analyses, historical information, and field survey observations. The fundamental physical and mechanical properties of the masonry elements were examined by incorporating stone blocks, mortars and core-infill materials. The mineralogical composition and interlocking textures of the collected samples were investigated utilizing a large range of complementary investigation and analysis techniques, including polarizing microscopy, X-ray diffraction (XRD), thermal analysis (TG/DTA), and environmental scanning electron microscope (ESEM) attached to an EDX unit. Through the results thus obtained, a complete characterization of the mineralogical composition; physical–mechanical, chemical, and thermal properties; and the interlocking textures of the construction materials of both the outer and inner-core layers was performed. The outer leaves of the majority of the multiple-leaf stone-masonry walls in medieval architectural heritage were mainly built of well-dressed limestone blocks with nearly uniform dimensions, while the inner-core layer was usually built of stone-rubble infill with bending lime-based mortar. The uniaxial compressive strengths of core infill (corresponding to the inner core layer) and lime-based mortar of the embedded joints are shown to be 85 and 92.5% lower than the limestone units of the outer layer, respectively. Moreover, experimental observations indicate that the inner core layer exhibits the highest porosity values; consequently, deteriorated, loose and cohesionless core infill could greatly affect the durability and thermal resistivity of this kind of wall. The results provide scientific support for investigating the overall structural behaviour of this type of walls and for decision-making in future conservation and restoration strategies.

Synthesis of Thermally Stable h-BN-CNT Hetero-Structures via Microwave Heating of Ethylene under Nickel, Iron, and Silver Catalysts

Initially, three samples of carbon nanotubes (SWCNTs) were synthesized from neem tree material. Afterward, these samples were coated with hexagonal boron nitride (h-BN) to form h-BN and CNT composite (h-BN-CNT). The essence of using h-BN (being a perfect insulator) with armchair SWCNT (being a conductor) is to create an interface between an insulator and conductor. The samples were treated under three different transition metal nanoparticles; silver, iron, and nickel. Thermogravimetric (TGA) analysis reveals that h-BN/CNT is thermally more stable with silver than iron and nickel nanoparticles. TGA profile showed resistance to mass loss at the beginning due to the higher thermal resistivity by the impurity compounds. The DFT calculation, generalized gradient approximation (GGA), and Perdew–Burke–Ernzerhof (PBE) analysis found engineered bandgap energy of 3.4 eV for the synthesized h-BN-CNT heterostructure. Because of its unique structural and electronic properties such as tunable bandgaps, the h-BN-CNT heterostructure may open new ways for manipulating excitons in the CNTs, and thus can be explored to develop various new electronic devices.