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BACKGROUND: Textile-sizing mill workers are exposed to various hazards in the sizing units during their working hours and are at risk of acquiring lung impairments due to the usage of sizing chemicals in the sizing process. OBJECTIVE: The main aim of this study is to assess the influence of cotton dust and sizing agents on lung function and breathing difficulties among Indian textile sizing mill workers. METHODS: This cross-sectional study was carried out at a textile-sizing mill from August 2022 to September 2022. A modified questionnaire based American Thoracic Society's standard was used to assess respiratory symptoms among sizing mill workers and the pulmonary function test was conducted Spirometry. The chi-square test was used to find the difference between respiratory symptoms and the t-test was used to find the difference between spirometric parameters. RESULTS: Textile sizing mill workers showed significant (Pâ< â0.0001) decline in peak expiratory flow rate, forced vital capacity (FVC), ratio of FEV1 and forced vital capacity, and forced expiratory volume in 1âs (FEV1). There was an association between symptoms and duration of exposure to pulmonary abnormality. Sizing mill workers showed a significant decline in lung functions and an increase in pulmonary symptoms. As the service duration of exposure in terms of years increased, respiratory symptoms increased and spirometric abnormality also increased. CONCLUSION: This study confirms that sizing agents such as polyvinyl alcohol (PVA), emulsifier, wax, carboxymethyl cellulose (CMC), and starch used in sizing mills are also responsible for respiratory illness and lung impairment among textile workers.
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Surface modification by suitable technique aids in improving the characteristics of material to resist severe wear in demanding environments and challenging applications. The present study aims to analyse the tribological performance of Stainless Steel (SS304) reinforced with CoCrCuFeTi High Entropy Alloy (HEA) through friction stir processing and compares the results with annealed specimens. The CoCrCuFeTi HEA was ball milled and revealed irregular fragment particles with Body Centred Cubic (BCC) phase. The processed samples exhibited excellent refinement in grains with uniform HEA reinforcement distribution. The grains were observed to be in nano level post-annealing promoting exceptional microhardness. The pin-on-disc wear test was conducted by varying load (10-40N), sliding velocity (0.5-3.5 m/s) and sliding distance (500-2000 m) and the respective worn surface was analysed. The processed sample with HEA after annealing offered 29.8%, 57.4% and 58.49% improved wear resistance at the minimum level of load, sliding velocity and sliding distance than the processed base samples. The worn morphology revealed delamination, abrasion, adhesion and oxide layer formation to be the predominant wear mechanisms.
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The deformation aspects associated with the micro-mechanical properties of the powder laser bed fusion (P-LBF) additively manufactured stainless steel 316L were investigated in the present work. Toward that, micro-pillars were fabricated on different planes of the stainless steel 316L specimen with respect to build direction, and an in situ compression was carried out inside the chamber of the scanning electron microscope (SEM). The results were compared against the compositionally similar stainless steel 316L, which was fabricated by a conventional method, that is, casting. The post-deformed micro-pillars on the both materials were examined by electron microscopy. The P-LBF processed steel exhibits equiaxed as well as elongated grains of different orientation with the characteristics of the melt-pool type arrangements. In contrast, the cast alloy shows typical circular-type grains in the presence of micro-twins. The yield stress and ultimate compressive stress of P-LBF fabricated steel were about 431.02 ± 15.51 - 474.44 ± 23.49 MPa and 547.78 ± 29.58 - 682.59 ± 21.59 MPa, respectively. Whereas for the cast alloy, it was about 322.38 ± 19.78 MPa and 477.11 ± 25.31 MPa, respectively. Thus, the outcome of this study signifies that the AM-processed samples possess higher mechanical properties than conventionally processed alloy of similar composition. Irrespective of the processing method, both specimens exhibit ductile-type deformation, which is typical for metallic alloys.
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Additive manufacturing (AM) of stainless steel is more difficult than other metallic materials, as the major alloying elements of the stainless steel are prone to oxidation during the fabrication process. In the current work, specimens of the stainless steel 316L were made by the powder laser bed fusion (P-LBF) additive manufacturing process. These specimens were investigated by electron microscopy and micro-/nano-indentation techniques to investigate the microstructural aspects and the mechanical properties, respectively. Compositionally, a similar wrought stainless steel was subjected to identical investigation, and used as a benchmark material. The microstructure of the P-LBF-processed alloy shows both equiaxed and elongated grains, which are marginally smaller (3.2-3.4 µm) than that of the wrought counterpart (3.6 µm). Withstanding such marginal gain size refinement, the increase in shear stress and hardness of the L-PBF alloy was striking. The L-PBF-processed alloy possess about 1.92-2.12 GPa of hardness, which was about 1.5 times higher than that of wrought alloy (1.30 GPa), and about 1.15 times more resistant against plastic flow of material. Similarly, L-PBF-processed alloy possess higher maximum shear stress (274.5-294.4 MPa) than that of the wrought alloy (175.9 MPa).
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Additive manufacturing (AM) of Ni-based super alloys is more challenging, compared to the production other metallic alloys. This is due to their high melting point and excellent high temperature resistance. In the present work, an Inconel 718 alloy was fabricated by a powder laser bed fusion (P-LBF) process and investigated to assess its microstructural evolution, together with mechanical properties. Additionally, the alloy was compared against the cast (and forged) alloy of similar composition. The microstructure of the P-LBF-processed alloy shows hierarchy microstructure that consists of cellular sub-structure (~100-600 nm), together with melt pool and grain boundaries, in contrast of the twin infested larger grain microstructure of the cast alloy. However, the effect of such unique microstructure on mechanical properties of the L-PBF alloy was overwritten, due to the absence of precipitates. The hardness of the L-PBF-processed alloy (330-349 MPa) was lower than that of cast alloy (408 MPa). The similar trend was also observed in other mechanical properties, such as Young's modulus, resistance to plasticity and shear stress.
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Tribological study of zirconia toughened alumina against alumina is investigated using ball-on-disk tribometer with different bio-lubricants. Friction and wear coefficients are estimated for these bio-lubricants under four different loading conditions which are equivalent to regular and risky human gait activities. Experiments are carried out for a total sliding distance of 10 km with each bio-lubricant to estimate its friction and wear coefficients. Using submodeling finite element approach, cumulative linear and volumetric wear is estimated with the help of contact pressure. The sesame oil bio-lubricant showed better wear coefficient for risky gait activities and Ringer's solution exhibited minimum wear coefficient for normal walking gait activity. Overall minimum cumulative linear and volumetric wear for 2 million cycles was obtained for Ringer's solution.
