This present research deals with the optimization study of biocement mortar made of biosilica, biochar, and egg shell waste powder to reduce the cement content up to 35 wt.%. The main purpose of this present study was to optimize the pozzolanic contents such as biosilica, biochar, and calcite egg shell particle in the setting time and water vapour transmission rate (WVTR) and compression strength of biocement mortar and how these bio-wastes turn to valuable material. The biocement mortar cubs were prepared using the Taguchi L9 design pattern and analysed followed by grey relational approach. The biosilica particle used here was extracted from rice husk ash followed by thermo-chemical method. Similarly, the porous biochar was prepared from rice straw followed by low-temperature pyrolysis. The egg shell waste powder was prepared via high-energy ball mill for about 4 h followed by sieving process to confirm the uniform particle size equal to 1 µm. The compression strength, WVTR, and final setting time were measured after the successful ageing of cement cubes for about 28 days. According to analysis, the experimental plan A3B1C3 gives overall best rank among other experimental patterns with the GRG of 0.705. Moreover, the weight percentage of biochar directly influences the overall performance of cement mortar cubes rather than biosilica and egg shell particles. The confirmation study revealed improvement in grey relational grade of 1.72%, which is equal to the high compression strength of 55.101 MPa, lower WVTR of 1.6E−6 kg/m2s at 28 °C, and lower final setting time of 521 min.

Pozzolanic biosilica, biochar, and egg shell in setting time, WVTR, and compression strength of biocement mortar: a Taguchi GRA validation

A review on additive manufacturing of alloys using laser metal deposition

The dissimilar metal combinations of SUS303 stainless steel and C19210 pure copper with a thickness of 0.2 mm by utilizing a nanosecond pulsed fiber laser was performed in lap welding with swing-spiral-trajectory. The weld effect was evaluated by means of microstructural and mechanical examinations. The influence of pulse frequency, speed and swing frequency as well as pulse waveform on mechanical properties and microstructure was clarified. The metallurgical behavior and weld penetration inside the fusion zone were observed with microscopic inspection of the welded joints and the welded surface. Part of molten pool materials inserted into copper plate formed an intertwined nails for enhancing the interfacial bonding strength was observed in the cross-section of the weldment. Additionally, the presence of a thin intertwined transition layer with solid solutions accomplished by the copper and liquid stainless steel mutual diffusion at the fusion line, indicated that the swing spiral welding pattern can strengthen the interface fusion. Some defects, such as porosities and microcracks, were also found in the welded joints. They were mainly due to the significantly different linear expansion coefficients of copper and steel. Energy dispersive spectroscopy (EDS) analysis confirmed that the interdiffusion and dissolution of copper and stainless steel occurred inside the molten pool, and the surface composition of the weld pool was dominated by iron. The microhardness (MH) study showed that the heat-affected zone (HAZ) was harder than the fusion zone on the stainless steel side, and the fusion interface microhardness much variation indicated microstructural change alongside the weld interface. The tensile test results revealed that the fracture location was in the molten pool on the stainless steel side, the fracture was protruded and the fracture mode was intergranular brittle fracture. 

Effect of Swing-Spiral-Trajectory on pulsed fiber laser welding stainless steel/Copper dissimilar metals

A brief review on the manufacturing of metal components using selective laser melting

In this work, low-carbon steel AISI-SAE grade 1010 with copper grade CDA 101 was joined by friction stir welding (FSW) using a tapered pin profiled tool. The rotational speed of the tool is 900 rpm, a traverse rate of 30 mm/min, and an axial force of 5 kN were used to produce the joints. The microstructural analysis and mechanical properties of the weld joints have been successfully examined. The optical microscopy, scanning electron microscopy, and X-ray diffraction (XRD) techniques were performed to examine the macropatterns and micropatterns of the welded joints. The tensile and hardness test was performed to evaluate the mechanical behaviours of the FSW joints. The fine ferrite grain features with uniform size were obtained in the microstructure of the nugget zone (stir zone). It is purely influenced by the alternating dynamic rearrangement (recrystallization) mechanism. High hardness was identified in the stir zone, even as the slightest stability was established in the heat-affected zone. The tensile investigation proposed that all the joints explored just lesser unbending nature than the parent material. The tensile strength of 181.5 MPa, the hardness of 144 VHN, and elongation of 14.03% were observed for the welded samples. The better properties for the weld joints were attained at 900 rpm spindle speed and tool traverse speed of 30 mm/min. The FSW is an attractive material joining process for both similar and dissimilar materials compared to other conventional types of joining processes, such as aerospace, marine engineering, shipbuilding, and industrial sector applications. 

https://www.scielo.br/j/mr/a/BKcpTZQvyf6Kw9YCGq86ztC/?lang=en&format=pdf

Microstructural Analysis and Mechanical Behaviour of Copper CDA 101/AISI-SAE 1010 Dissimilar Metal Welds Processed by Friction Stir Welding

This present work investigates the effect of adding novel biochar microparticle into the welding zone of dissimilar friction stir welding of AISI-SAE 1010 (steel)–CDA 101 (copper) alloys. The primary aim of this work was to produce efficient weld joints in AISI-SAE 1010–CDA 101 alloys using biochar as solid lubricant via friction stir welding process. The biochar particles were prepared from rice husk biomass via carbonization process. The welding was performed using tapered pin profiled tool with rotational speed of 900 rpm, traverse speed of 30 mm/min, axial load of 5 KN, dwell time of 5s, plunging depth of 0.2mm, and biochar additions of 0.5, 1, 2, and 4wt%. The highest tensile strength of 205 MPa, elongation of 44%, yield strength of 177MPa, strain value of 36, and Vickers hardness of 121 were observed for FSW joints made using 2wt% of biochar content. Large addition of biochar up to 4wt% marginally affects the properties. Similarly, the fatigue strength of 157MPa was observed for weld made using 2wt% of biochar. The microstructure of biochar-assisted weld nugget shows highly refined less thermally affected grains. The grains were in equiaxial with distortion-free. The EDAX report confirms the presence of copper, iron, and carbon on the weld nugget, which indicates fine mixing of parent metals with solid lubricant. These mechanical properties improved environmental friendly dissimilar welding method could be used in industrial applications such as automobile, aerospace, construction, defense, medical, energy where high strength with high durable weld joints are required to meet the current technology demand, and process economy.

B. Yokesh Kumar

Papers

Biochar-assisted copper-steel dissimilar friction stir welding: mechanical, fatigue, and microstructure properties