Abstract The Underwater Friction Stir Welding (UFSW) environment was proven to improve mechanical properties of the Friction Stir Welded (FSW) joints. However, carefully selected set of parameters is necessary to succeed. This study presents preliminary results of the research on water salinity level effect on the properties of the AA5754 aluminum alloy joints. For this purpose, the Plackett-Burman design was used. The design of experiment consists of ten attempts with process parameters as variables: welding speed, rotational speed, tool tilt angle and water salinity level. The following tests were proceeded: visual tests, tensile strength tests and fractography analysis. Thus, the response variable was ultimate tensile strength (UTS). Surface defects were found in joints performed with low heat input (i.e. low rotational speed, high welding speed). The highest UTS values – 100% of base metal were obtained for the joint made with process parameters: welding speed - 37.5 mm/min, rotational speed - 1235 rpm, tool tilt angle - 2°, water salinity level - 10%. The fractography of the joint revealed precipitates formation and very small dimples. All of the investigated welding parameters were found to be statistically significant. However, the tool tilt angle was of drastically highest significance. The order of the other process parameters was as following: welding speed, rotational speed and water salinity level.

Abstract This study examines the influence of print orientation and printing speed on the mechanical strength and surface roughness of components fabricated from Polylactic Acid (PLA) using the Fused Deposition Modeling (FDM) process. The 3D-printed samples were produced with varying orientations (0°, 90°, and 45°) and print speeds, while other parameters remained constant. All samples had a 100% infill density, a “Lines” infill pattern, and a printing temperature of 210°C. The 0° and 90° samples were printed at 50 mm/s, whereas the 45° samples were printed at 40, 60 and 80 mm/s. Each sample was printed three times to ensure repeatability and obtain an average result. The results indicate that raster angle plays a critical role in determining mechanical performance, with 0° and 90° orientations yielding the highest 72.31 MPa and lowest 56.26 MPa stress values, respectively. Additionally, a nuanced relationship was observed between printing speed, surface roughness, and tensile strength. Surface roughness metrics, including Ra, Rz, and Rq, improved with decreasing printing speed, indicating enhanced surface finishes. The optimal tensile strength of 57.95 MPa was achieved at a moderate printing speed of 60 mm/s, offering the best balance between mechanical strength and surface quality. This research enhances the understanding of parameter optimisation in FDM processes, providing practical insights for the production of high-performance PLA-based components.

Abstract The machinability of two copper alloys with lead: CuZn40Pb2 and CuSn5Zn5Pb2, was assessed. Turning tests were performed based on the selection of parameters that will result in the tool being worn out after 1 minute. Tool wear was assessed by observing dimensional and microstructural changes in the blade. When assessing machinability, power consumption, chip shape, changes in the surface layer and surface roughness were taken into account. The research aims to determine the custom machinability index of materials used in SANHA Polska. A publicly available index must be adapted to a given application, and such adaptation is often quite time-consuming. Therefore, a 1-minute test was carried out as a quick and cheap alternative to a large fleet of machines with various machining properties. The developed methodology and the results obtained are the basis for further research conducted as part of the implementation doctorate, the aim of which is to implement the production of well-machinable lead-free materials for drinking water installations, characterized by good solderability and corrosion resistance. As a result of the conducted research, the role of lead in the machining of copper alloys was identified, which is important due to European restrictions on the elimination of this element and its replacement in a way that allows for precise removal processing.

Abstract Atmospheric plasma spraying (APS) allows deposition of ceramic coatings on metallic substrate, significantly increasing the wear resistance of the component. Coating’s microstructure and consequently its properties, depend on heat treatment of the feedstock particles. This property can be controlled by process parameters, especially electric power and spray distance. On the other hand, some plasma torches allow introducing another variable, an injection mode, which could be realized in external or in internal way. In the presented research, wear resistance of Al 2 O 3 +13 wt.% TiO 2 coatings deposited under various values of spray distance and different injection modes were examined using ASTM G-99 procedure. The impact of spraying parameters on the coating’s microstructure was established and connected to the functional properties of the manufactured deposits. Observed differences indicated influence of injection mode and spray distance value. Coatings deposited with internal feedstock injection exhibit lower porosity and slightly higher hardness than these made with external injection mode. In terms of wear resistance for both spray distance the wear factor was lower for internal injection system. Obtained results confirmed assumed thesis, that internal injection mode improves heat treatment and consequently ameliorate wear performance of plasma sprayed alumina-titania coatings.

Abstract In this study, the effect of using waste granodiorite powder (WGP) as a cement replacement material in percentages ranging from 1 to 9% on various physical and mechanical properties of ordinary concrete was investigated. The resistance of produced concretes with WGP to the high temperature effects on the 28 days compressive strength were studied as well. Granodiorite is one of the well-known igneous rocks that have been used in previous research as a replacement for coarse or fine aggregates due to the hardness of its grains. However, rare studies have investigated its powder as a partial cement replacement material. Results showed the ability of investigated WGP with high surface area to act as a supplementary cementitious material that contributed to enhance the results of mechanical and physical properties of concrete. At traditional room temperature, the optimal replacement percentage was 7%, where the 28 days compressive and tensile strengths were improved by 28.3% and 17.3%, respectively. The optimal replacement ratio varied between 7 and 9% in the case of high temperatures, according to exposure time and temperature degree. Statistical and sensitivity analysis was conducted on 66 available compressive strength value represents all variables before and after elevated temperature exposure. While the regression equation showed good R 2 value of 85.3%, sensitivity analysis indicated that compressive strength value is most sensitive to temperature, followed by WGP ratio and exposure time, with importance values of 56, 26, and 18 %, respectively. Results showed also that the setting times and consistency was decreased with increasing the replacement ratio with WGP, while the workability was slightly improved up to 5% replacement ratio. Furthermore, microstructure analysis showed that WGP can help to densify the concrete matrix due to its small size and ability to fill the interstitial voids in the concrete matrix.

Abstract In present study mass loss behaviour of base metal and heat-treated API X70 pipeline steel in different environments such as fresh water, sea water and sodium thiosulphate medium were observed for 50 days. Corrosion is the main failure in pipeline steel which need to be reduced with the use of suitable heat treatment process. In present study two heat treatment such as HT-1 900 °C (2 hour) with tempering at 450 °C (4 hour) and HT-2 800 °C (2 hour) with tempering at 450 °C (4 hour) was used. Mechanical, microstructure and corrosion rate of HT-1 and HT-2 specimen in different environments were observed. Maximum corrosion rate (0.306 mm/y) in fresh water while minimum corrosion rate (0.181 mm/y) in sodium thiosulphate medium was observed for base metal. Maximum corrosion rate (0.224 mm/y) in sodium thiosulphate while minimum corrosion rate (0.106 mm/y) in fresh water medium was observed for HT-1 specimen. For HT-2 specimen, Maximum corrosion rate (0.192 mm/y) in sea water while minimum corrosion rate (0.099 mm/y) in fresh water medium was observed. For HT-2 specimen, maximum average hardness of (30.3 HRC) in sea water while minimum average hardness of (28 HRC) of base metal was observed. In fresh water also HT-2 specimen, maximum average hardness is (26.3 HRC) while minimum average hardness of (24.6 HRC) of base metal was observed. After that maximum average hardness of base metal (26.6 HRC) in sodium thiosulphate while minimum average hardness of (21 HRC) of HT-2 specimen was observed.

Abstract The main objective of this paper research is a comparative study on the effect of the glass powder (GP) substitute from collected and recycled glass waste, as a fine partial cement replacement on the mechanical performance and durability of high performance concrete (HPC) and ordinary concrete (OC). For this two cement dosing were used of 400 kg/m 3 to formulate OC and 450 kg/m 3 to formulate HPC, and GP as considered binder like cement and not as fine addition, hence binder represent the sum of cement with GP (L=C+GP) with which will be made our two concretes formulation. Two ratios were used for the Water/Binder (W/B), the first W/B=0.35 for the HPC and the second W/B=0.5 for the OC, this ration is very important to fix the concentration of superplasticizer. A percentage of 10% and 20% substitution of cement CPA without additions noted CEM I 52.5 by the glass powder with fineness of 3600 cm 2 /g are used. The evaluation of the compressive strength was followed from 7 to 365 days in order to study the behavior of the GP at different ages affected by the cement dosing and the ratio W/B compared to the reference concrete without GP for the two concretes HPC and OC. At 28 days the strengths of concretes with GP is affected by the replacement of a quantity of cement since the two reference concretes were superior but beyond this age an inverse behavior is noticed such that results obtained at age of 365 days seem to be advantageous in terms of savings in the quantity of cement used by interpreting the compressive strength, and the decrease in quantity of water in the mixtures offers a remarkable difference between the two concretes studied by using 20 % of GP as replacement of cement.

Abstract This paper investigates the reinforcement of rigid polyurethane foams with microcrystalline cellulose to improve their mechanical and thermal properties. In this work, microcrystalline cellulose was added to polyol and was dispersed using two methods: calendering and ultrasounds. As a result of the study, it was found that the addition of micro cellulose to the polyol mixture used for the synthesis of polyurethane foam changes the properties of the final product. A crucial aspect is how it is added to the mixture. When adding microcrystalline cellulose particles, better results were obtained for particles dispersed using ultrasound. The most beneficial changes were obtained for the sample with 2php cellulose. The most significant reduction in average pore size was shown, which has a beneficial effect on the insulating properties of polyurethane foam. In addition, an increase in mechanical properties was also noted. Both properties are highly desirable in many applications.

Abstract The objective of the study is the chemical synthesis of ZnO powders, from ZnCl2 and NaOH solutions according to an appropriate procedure. The powders (a) and (b) obtained underwent various characterizations such as: optical microscopy, SEM, UV, BET, IR, XRD and antimicrobial activity. The results showed the inhomogeneous distribution, the nanometric size, the absorbance at 353 and 346 nm and the specific surface of 25.701 and 30.534 cm2/g of the particles, the presence of all the characteristic bands of ZnO which was confirmed by XRD and very good bacterial sensitivity of the two ZnO powders.

Abstract In sheet metal forming processes, friction increases the force parameters of the forming process and produces a deterioration in the quality of the surface of the components. The basic way to reduce the unfavourable impact of friction is to lubricate the sheet metal surface with commercial oils. This article presents the results of experimental studies and analysis of variance (ANOVA) of the friction of DC01 low-carbon steel sheets using a strip drawing test. For these tests, a special device was built containing countersamples with a flat surface made of 145Cr6 steel covered with a protective AlTiN coating. Lubricants of different viscosities were fed into the contact zone under forced pressure. The effect of contact pressure on the value of the coefficient of friction was also determined. The predicted R² of 0.9227 was in reasonable agreement with the adjusted R² of 0.9411 confirming that the ANOVA model was reliable. It was found that increasing the lubricant pressure had a beneficial effect in reducing the value of the coefficient of friction. The higher the contact pressure, the more effectively the pressurised oil reduced the value of the coefficient of friction.