Friction Stir Processing of Additively Manufactured Ti-6Al-4V Alloy: Structure Modification and Mechanical Properties

This work explores the possibility of using friction stir processing to harden the Ti-6Al-4V titanium alloy material produced by wire-feed electron beam additive manufacturing. For this purpose, thin-walled workpieces of titanium alloy with a height of 30 cm were printed and, after preparation, processed with an FSW-tool made of heat-resistant nickel-based superalloy ZhS6U according to four modes. Studies have shown that the material structure and properties are sensitive to changes in the tool loading force. In contrast, the additive material’s processing direction, relative to the columnar grain growth direction, has no effect. It is shown that increasing the axial load leads to forming a 𝛽-transformed structure and deteriorates the material strength. At the same time, compared to the additive material, the ultimate tensile strength increase during friction stir processing can achieve 34–69%.

Bioplastic Production from Eucheuma Cottoni

Plastic waste has become a global problem because it causes environmental pollution. This is because plastic waste is difficult to decompose. There have been numerous solutions proposed, one of which is theuse of bioplastics. In this research, the bioplastics were made from third- generation biomass, namely the eucheuma cottoni. Eucheuma cottoni is contains biopolymer carrageenan, a carbohydrate with unit structures consisting of d-galactose and 3,6 anhydrogalactose with glycosidic bonds. Goal this research is study the effects of sorbitol plasticizer content and bioplastics manufacturing temperature on bioplastics, tensile strength, elongation, and biodegradation rate. The bioplastics were made by extracting 10 grams of eucheuma cottoni powder in 200 ml of distilled water. The algae extract was added with sorbitol (plasticizer) and heated at various temperatures from 45°C until 60°C. The mixture was poured into a mold tin and dried in the oven to a constant weight. The resulting bioplastics were then characterized to determine the tensile strength and biodegradation rate. The results showed that increasing the plasticizer content from 3.5% reduced the tensile strength, however, it increased the elongation and biodegradation rate. The optimal plasticizer content was 4% with a tensile strength value of 4.8309 Mpa, elongation of 24.1548%, and biodegradation rate of 26.9392%. The temperature variable showed that increasing the temperature of making bioplastics could reduce tensile strength, increase elongation and biodegradation rate of bioplastics. The optimum temperature for making bioplastics at 45oC obtained a tensile strength of6.28 Mpa and an elongation of 20.67%. The biodegradation rate was 39.6665%, and the best sorbitol content was received at 4%.

Friction Stir Welded AA5052-H32 under Dissimilar Pin Profile and Preheat Temperature: Microstructural Observations and Mechanical Properties

In order to meet the escalating demand in the shipbuilding business, suitable materials with enhanced qualities are required to maximize ship cargo while reducing fuel consumption. Aluminum (Al) and its alloys are competing contenders for use in a variety of complicated ship structures. The major challenge to enhancing joint quality and performance is the quest for a viable and efficient FSW parameter. The main focus of this study was to critically explore the effect of the tool pin profile and the preheat temperature used during the friction stir welding of AA 5052-H32 on its mechanical properties and weld microstructure characteristics. There are three pin profile variations, including samples that were cylindrical, samples with two flat sides, and samples with three flat sides, all of which were investigated in different preheat temperatures (150–300 °C). The results that were obtained during macrographic observation showed that tunnel defects were visible in the cylindrical and two-flat-sided pin profile designs. During observations of the microstructure, it was observed that the grain size became finer and smaller in the weld nugget compared to in the heat affected zone (HAZ) and thermo-mechanically affected zone (TMAZ) regions due to dynamic recrystallization. However, at the 300 °C preheat variation, the grain size appeared to be larger due to the slower cooling rate, causing a decrease in the mechanical properties of the samples. The results of the physical tests determined that the preheat temperature caused an increase in the mechanical properties until 250 °C, at which point the three-flat-sided pin profile tool demonstrated superior mechanical properties compared to the tools with a cylindrical design; a 12.2% tensile strength increase, a 15.3% and 9.4% face and root bending increase, and an 11.2% hardness increase were observed.

The Use of Controlled Dissolution Glass for the Consolidation of a High Porosity Chalk

This paper reports the development and testing, of a Phosphate controlled dissolution glass composition used to strengthen the matrix of chalk whilst retaining the permeability of the rock, facilitating improved hydrocarbon recovery in unstable wells. Multiple versions of the glass solutions and different types of colloidal silica were extensively tested in the laboratory to determine injectability and reactivity with calcium carbonate rocks. The goal of the testing was to determine the best performing solution for use in a field trial in the Norwegian North Sea. The laboratory testing included filtration and core flood tests to determine the injectability of the solutions and post treatment permeability, and Brazilian strength tests to determine the tensile strength of the treated chalk cores. The filterability was tested through filter screen sizes ranging from 5 to 0.6 µm. Core flood testing was performed on 10 cm long chalk cores with 1.5 mD permeability. The glass solutions showed the best results in the filtration and core flood testing, achieving significantly greater invasion depth than any of the colloidal silica samples. The phosphate glass treated chalk cores maintained 70 to 100% of the original permeability while delivering a 3 to 5 fold tensile strength increase. The lab tests demonstrated the potential of a glass based treatment to strengthen chalk formations without impeding permeability.Based on the promising results from the lab tests, it was decided to trial the selected glass solution in a mature vertical proppant fractured well. The test confirmed that the glass solution could be pumped into the well, but the test failed pre-maturely after two months of varied production, and the trial will not be covered in this paper.However, due to the high value in being able to stabilize chalk in the field, the Operator is evaluating a new trial in a horizontal well, and learnings from the first trial will be used to inform further lab tests in the next phase. The glass solution used in this trial is being further developed to be used in other formation types, such as sand and non-calcium containing reservoirs.

Influence of Nickel on the Microstructure and Mechanical Properties of Nodular Cast Iron

This research investigates the nickel content added by 1.1wt%, 2.2wt%, 3.7wt% and 4.5wt% on the microstructure and mechanical properties in the nodular cast iron. The results demonstrate that the microstructure of nickel addition consists of nodule graphite, ferrite and pearlite phase while nickel was added to 4.5 wt% the microstructure becomes ferrite transform to fully pearlite phase. In addition the ductile iron has the highest nodularity (0.79%), followed by 1.1%Ni (0.75%), 2.2%Ni (0.71%), 3.7%Ni (0.69%) and 4.5%Ni (0.58%). The hardness and tensile strength increase when increasing the nickel content. Elongation is enhanced with nickel increasing and reaches a maximum of 12% at 1.1 wt% Ni, then decreases with the further increase of nickel.

Effect of Quantity of Industrial Waste on Eco-Friendly Geopolymer Concrete

The primary goal of this work is to report the results of the experimental outcome of Geopolymer concrete (GEO-C) which is prepared and cured at room temperature. GEO-C is prepared using a blend of ground granulated blast furnace slag (GGSG) and F Class Fly Ash, and the replacement is ranged from 0% to 100% of binder material, to find the optimum dosage of binder material. Sodium Hydroxide (NaOH) and Sodium Silicate (Na2SiO3) which are alkaline in nature, used primarily as an activating agent for the polymerization process of geopolymer. Experiments were conducted on samples by fixing the NaOH concentration as 14M for optimum strength and the alkaline activator ratio is fixed as one. Mechanical properties of GEO-C like compressive strength, rupture modulus (i.e. flexural strength), and split tensile strength were evaluated at the ages 7, 14, 28 days. From the results, it is observed that with the addition of GGSG in the blend the compressive, flexural, and tensile strength increase but there is a drastic reduction in the workability of the mixture.

Efficient Gas Barrier and Antibacterial Properties of Poly(lactic acid) Nanocomposites: Functionalization with Phytic Acid–Cu(II) Loaded Layered Clay

Poly(lactic acid) (PLA) represents one of the most promising and attractive bio-based polymers for green packaging. However, toughness, gas barrier and antibacterial properties of pure PLA films cannot compete with those of traditional petroleum-based active packaging plastics. To fill this gap, utilization of excellent chelating properties of phytic acid (PA), functionalized layered double hydroxides (LDHs@PA-Cu(II)) was firstly synthetized via facile deposition and chelation of one-step assembled PA-Cu(II) coordination compounds on the surface of layered clay. Furthermore, LDHs@PA-Cu(II)/PLA nanocomposites were prepared by blending LDHs@PA-Cu(II) and pure PLA via solution casting evaporation process. After adding only 1 wt % LDHs@PA-Cu(II), elongation at break and tensile strength increase by 53.0% and 18.9%, respectively, and the oxygen relative permeability decreases by 28.0%. Due to the strong interface interaction and heterogenous nucleation, the reinforcement effect of LDHs@PA-Cu(II) at low loadings is remarkable. Meanwhile, owing to the antibacterial activity of PA-Cu(II) coatings, the antibacterial rate (against Escherichia coli) of LDHs@PA-Cu(II) exceeds 99.99%. Furthermore, the corresponding LDHs@PA-Cu(II)/PLA nanocomposites also show outstanding antibacterial properties, which will be a promising candidate for active packaging application.

The Influence of Granite Cutting Waste on The Properties of Ultra-High Performance Concrete

This study analyzes the effect of using waste by-products generated in the process of granite cutting as part of the granular structure of Ultra High Performance Concrete (UHPC). The manufactured concrete has a compressive strength greater than 115 MPa. This study substitutes 35%, 70% and 100% of the volume of micronized quartz powder (<40 μm) with granite cutting waste. This is an innovative study where the feasibility of using waste from granite quarries as a replacement for micronized quartz in UHPC has been analyzed. The results show an improvement in the workability and compressive strength of UHPC, for all substitution ratios. The flexural strength and tensile strength increase when the substitution ratio is 35%, and even the values obtained for 100% substitution are acceptable. In view of the results obtained in this study, granite cutting waste, instead of the micronized quartz powder usually used, is a viable alternative for the manufacture of expectedly more sustainable UHPC.

Processing and Properties of MDF Fibre-Reinforced Biopolyesters with Chain Extender Additives

Biopolyesters are a way to improve natural fibre composite sustainability. This study explores, for the first time, the potential of using medium density fibreboard (MDF) fibres to reinforce four biobased and biodegradable polyester matrices to create a fully “green composite.” Added at 30 wt %, MDF fibres did not improve the strength of the injection moulded NFCs and this deficiency was investigated by measuring fibre length, viscosity, and molecular weight of the matrices. Compared to other lignocellulosic fibres, the use of MDF fibres led to a molecular weight reduction of biopolyesters during processing. This effect was particularly striking for PLA. The addition of a chain extender enhanced the molecular weight of PLA and improved its processability. The tensile strength increase was correlated to a reduction of fibre pull-out, enabling the MDF fibre to fulfil its expected reinforcement role within the biopolyester composite.

Synthesis, Structure and Mechanical Properties of Bulk “Copper-Graphene” Composites

Bulk copper, copper-graphene and copper-graphite composites were produced from copper-thermally expanded graphite (TEG) powder mixtures with 0-3 wt.% TEG contents via modified powder metallurgy process that includes powder milling in a planetary mill at 350 rpm for 5 hours, compaction, and vacuum annealing at 1030 °C for 1 hour. Phase composition and microstructure of the composites were analysed by XRD and SEM techniques. According to Raman spectroscopy, TEG transforms into a few layer graphene flakes in case of composites with 0.1-1 wt.% of carbon additive, while for 3 wt.% of carbon additive it remains in the form of graphite. The addition of 0.1 wt.% TEG results in the tensile strength increase up to 160 MPa (from 93 MPa for pure copper specimen synthesized via the similar synthesis route). Vickers hardness obtained for Specimens under the study is independent fromthe composite composition.