Vacuum brazing of titanium alloy to stainless steel enhance by fiber laser surface texturing

A method for improving the brazing joining strength of Titanium alloy/Stainless steel fabricated through fibre laser surface texturing is introduced because it is a simple process that does not require the fabrication of complicated interlayers. However, previous research shows that a milimeter scale was fabricated by surface modification for dissimilar brazing join, yielding insignificant results and limiting the application and degree of enhancement. Fiber laser ablation was used in this study to create microscale periodic patterns (grooves) on a stainless steel surface. No defect or damage induced during laser surface texturing process. The groove dimension was tunable by controlling the laser parameters. Vacuum brazing of Ti6Al4V to 316L stainless steel with surface texturing, the average joint strength was 22.1 MPa, 34% of increase of joining strength compared to unprocessed flat surface. The combination of laser surface texturing and brazing proven effectively on joining strength enhancement

Effect of laser surface modification on SS316L surface roughness and laser heating temperature

Nowadays, stainless steel is widely used in laser processing applications, including laser heating, laser brazing, and laser welding. However, it has poor optical properties due to low laser energy absorption. However, this could be improved with the aid of laser surface modification (LSM). The significance of this work is to examine the influence of LSM laser power on the surface roughness of 316L stainless steel samples. First, the LSM laser power was varied from 15 to 27 W. Then, the surface topography and variation of the surface roughness values were examined by using a 3D optical microscope. Furthermore, the modified surface by LSM will be heated using laser radiation in order to analyze the effect of surface roughness towards laser heating temperature. The result revealed that as the LSM power increased, thereby resulting in an increase of surface roughness. The highest LSM laser power (27 W) produced the highest surface roughness with 28.98 μm. Experimental results illustrate that the heating temperature were increased 36%, corresponding to a polished flat reference surface, which indicates the increment in energy absorptivity

Tailoring the dispersibility of non-covalent functionalized multi-walled carbon nanotube (MWCNT) nanosuspension using shellac (SL) bio-resin: Structure-property relationship and cytotoxicity of shellac coated carbon nanotubes (SLCNTs)

This study first reports the use of natural thermoplastic bio-resin shellac (SL) to functionalize multi-walled carbon nanotubes (MWCNTs). The MWCNTs were coated with 5, 10, and 15 wt% SL solutions to fabricate SLCNT nanocomposites which are highly dispersible and stable in solution. Enhanced surface charge imparted long-term stabilization of SLCNT nanosuspension. Microscopic analysis revealed distinct dispersion of nanotubes and a thin layer of SL on the surface of nanotubes in the nanocomposite system. FTIR and Raman spectroscopy confirmed well interaction between SL and MWCNT in the nanocomposites. It was disclosed by the microstructure analysis that the SL concentration affects the lattice parameters of SLCNT nanocomposites. The thermal stability of SLCNT was impressive compared to MWCNT. According to the ROS (reactive oxygen species) generation profile and cell viability study, SLCNTs have reduced adverse effects on cells. Therefore, the results confirm that shellac can significantly improve the stability of MWCNT and reduce the cytotoxicity to facilitate their widespread applications

Cost-effective management of ufra disease of rice and identification of resistant landraces

A series of trials were undertaken to evaluate 3 nematicides, marshal 6G, diafuran 5G and pilarfuran 5G @ 1.0 kg ai/ha along with standard cheek, furadan 5G and to explore the resistant genotypes against ufra disease caused by Ditylenchus angustus in the rain-fed and irrigated ecosystems during 2001 to 2004. All the tested nematicides were effective to control the ufra disease of rice and increased yield compared to control (diseased). In respect of all seasons, marshal 6G, diafuran 5G, pilarfuran 5G increased yield by 3.35 to 5.10, 3.23 to 5.00 and 3.26 to 4.90 t/ha, respectively over the control (diseased). Yield loss due to ufra disease was 87.85% in the rain-fed rice, while it was 90.82% in the irrigated rice in artificial inoculation condition. In simple profitability analysis, marshal 6G, diafuran 5G and pilarfuran 5G showed 16.20, 15.76 and 15.58 times profitable in the rain-fed rice and 20.40, 20.11, 19.68 and 20.58 times profitable respectively, over the control (diseased) in the irrigated rice. So, the application of 3 nematicides, marshal 6G, diafuran 5G and pilarfuran 5G @ 1k ai/ha were effective in controlling ufra disease and could be used as alternative to furadan 5G. Of 40 landraces of rice tested, 5 (Daudin Da-21, Lambo Sail, Madhu Sail, Bhawalia Aman and Lal Chamara) showed highly resistant against ufra disease

State-of-the-art and future perspectives of environmentally friendly machining using biodegradable cutting fluids

The use of cutting fluids has played a vital role in machining operations in lubrication and cooling. Most cutting fluids are mineral oil-based products that are hazardous to the environment and the worker, cause severe diseases and pollute the environment. In addition, petroleum resources are becoming increasingly unsustainable. Due to environmental and health issues, legislations have been established to ensure that the consumption of mineral oil is reduced. Consequently, researchers are making efforts to replace these mineral oil-based products. Vegetable oils are grasping attention due to their better lubricating properties, ease of availability, biodegradability, low prices, and non-toxicity. In this study, a detailed review and critical analysis are conducted of the research works involving vegetable oils as cutting fluids keeping in view the shortcomings and possible solutions to overcome these drawbacks. The purpose of the review is to emphasise the benefits of vegetable oil-based cutting fluids exhibiting comparable performance to that of mineral oil-based products. In addition, an appropriate selection of non-edible vegetable oil-based cutting fluids along with optimum cutting parameters to avoid a scanty supply of edible oils is also discussed. According to this research, vegetable oils are capable of substituting synthetic cutting fluids, and this option might aid in the successful and cost-efficient implementation of green machining

A comprehensive assessment of laser welding of biomedical devices and implant materials: recent research, development and applications

This review comprehensively covers the research accomplished in the field of laser welding of biomedical devices and implant materials. Laser welding technology in the recent past has been envisaged for numerous biomedical applications encompassing the reconstruction, fabrication, joining and sealing of the implanted biomaterials. It is the most studied and an increasingly applied manufacturing technology that garners the distinct advantages of smaller beam diameters leading to minimal thermal cycles that reduce the size of heat affected zone and instigate microstructural refinement. This paper presents a detailed critical review of similar and dissimilar welding of titanium alloys, cobalt-chromium alloys, steel, bulk metallic glasses and polymer-based biomaterials. Mechanical properties of the welded joints such as fatigue load, tensile and flexural strength, elongation, hardness and modulus of elasticity are discussed. The effect of laser processing parameters on microstructural features and the corresponding metallurgical defects encountered such as cracks, porosities, voids or the loss of alloying elements are reviewed. Furthermore, the corrosion behavior, cytotoxicity and biocompatibility of the welded implants in the simulated mediums are discussed. Furthermore, this article also summarizes the present-day applications associated with implant materials and is aimed at the further involvement of the laser precision technology in producing materials and joints with desired biomechanical characteristics. Lastly, the current research gaps on the role of laser welding of implants and the anticipated emerging fronts are summarized

Determinants of Managerial Values on Corporate Social Responsibility: Evidence from China

This paper empirically investigates how Chinese executives and managers perceive and interpret corporate social responsibility (CSR), to what extent firms’ productive characteristics influence managers’ attitudes towards their CSR rating, and whether their values in favour of CSR are positively correlated to firms’ economic performance. Although a large proportion of respondents express a favourable view of CSR and a willingness to participate in socially responsible activities, we find that the true nature of their assertion is linked to entrepreneurs’ instincts of gaining economic benefits. It is the poorly-performing firms, or rather, firms with vulnerable indicators – smaller in size, State-owned, producing traditional goods and located in poorer regions that are more likely to have managers who opt for a higher CSR rating. Managers’ personal characteristics per se are not significant in determining their CSR choice. Moreover, controlling for other observed variables, we find that managers’ CSR orientation is positively correlated with their firms’ performance. The better-off a firm is, the more likely its manager is to get involve in CSR activities. Firms with better economic performance before their restructuring would sustain higher post-restructuring performance

Co-encapsulation of human serum albumin and superparamagnetic iron oxide in PLGA nanoparticles: Part I. Effect of process variables on the mean size

PLGA (poly d,l-lactic-co-glycolic acid) nanoparticles (NPs) encapsulating magnetite nanoparticles (MNPs) along with a model drug human serum albumin (HSA) were prepared by double emulsion solvent evaporation method. This Part I will focus on size and size distribution of prepared NPs, whereas encapsulation efficiency will be discussed in Part II. It was found that mean hydrodynamic particle size was influenced by five important process variables. To explore their effects, a five-factorial, three-level experimental design and statistical analysis were carried out using STATISTICA® software. Effect of process variables on the mean size of nanoparticles was investigated and finally conditions to minimize size of NPs were proposed. GAMS™/MINOS software was used for optimization. The mean hydrodynamic size of nanoparticles ranged from 115 to 329 nm depending on the process conditions. Smallest possible mean particle size can be achieved by using low polymer concentration and high dispersion energy (enough sonication time) along with small aqueous/organic volume ratio