Abrasive water jet machining of fly ash and metakaolin based geo-polymers

In the present study, the abrasive water jet machining (AWJM) of geopolymers prepared from fly ash, metakaolin and sand is discussed. The samples were prepared from sodium promoter, fly ash / metakaolin and sand. The process of activation was made using a 10M sodium hydroxide solution combined with a sodium silicate solution (the ratio of liquid glass - 1:2.5). To produce geopolymers, flakes of technical sodium hydroxide were used and an aqueous solution of sodium silicate (R-145) with a molar module of 2.5 and a density of around 1.45 g/cm3 the tap water. The alkaline solution was prepared by means of pouring the aqueous solution of sodium silicate over the solid sodium hydroxide. The solution was mixed and left until its temperature stablised and the concentrations equalised, which took around 2 hours. The fly ash, sand and alkaline solution were mixed for around 10 minutes using a low-speed mixing machine (in order to obtain a homogeneous paste). The paste was allowed to dry in the shade. The paper investigates the AWJM studies on the prepared geopolymer specimens with varyied input parameters such as standoff distance (1.2 and 3 mm), water pressure (120, 140 and 160 MPa) and feed rate (5, 10 and 15 mm/min). The output parameters such as kerf angle and material removal rate (MRR) were studied with the varying combination of input parameters. From the results, the optimal parameters for machining the geopolymer composites were interpreted

The Influence of Tuff Particles on the Properties of the Sintered Copper Matrix Composite for Application in Resistance Welding Electrodes

This paper presents modern copper-matrix composite materials in which volcanic tuff particles are used as a reinforcing phase. The aim of the research was to determine the optimal shares of volcanic tuff additive based on such criteria as softening temperature, relative density, electrical conductivity, and hardness. The properties of the produced and tested composites allowed us to determine the usefulness of this type of material for resistance welding electrodes. To confirm the assumptions made, preliminary investigations of the durability and behavior of electrodes made of the tested material during the processes of welding non-alloy steel sheets were carried out. As a result of the research, it was discovered that the addition of 5% tuff produces the best results in this type of composite. It was found that for the sample with a 5% share of tuff, a high softening point above 600 °C was obtained, high hardness after densification at the level of 62 HRB, and high relative density of approximately 95% and very good conductivity at the level of approximately 45 MS/m. The conducted tests did not show any electrode wear different from the commonly used alloys for resistance welding

Abrasive water jet machining of fly ash and metakaolin based geo-polymers

In the present study, the abrasive water jet machining (AWJM) of geopolymers prepared from fly ash, metakaolin and sand is discussed. The samples were prepared from sodium promoter, fly ash / metakaolin and sand. The process of activation was made using a 10M sodium hydroxide solution combined with a sodium silicate solution (the ratio of liquid glass - 1:2.5). To produce geopolymers, flakes of technical sodium hydroxide were used and an aqueous solution of sodium silicate (R-145) with a molar module of 2.5 and a density of around 1.45 g/cm3 the tap water. The alkaline solution was prepared by means of pouring the aqueous solution of sodium silicate over the solid sodium hydroxide. The solution was mixed and left until its temperature stablised and the concentrations equalised, which took around 2 hours. The fly ash, sand and alkaline solution were mixed for around 10 minutes using a low-speed mixing machine (in order to obtain a homogeneous paste). The paste was allowed to dry in the shade. The paper investigates the AWJM studies on the prepared geopolymer specimens with varyied input parameters such as standoff distance (1.2 and 3 mm), water pressure (120, 140 and 160 MPa) and feed rate (5, 10 and 15 mm/min). The output parameters such as kerf angle and material removal rate (MRR) were studied with the varying combination of input parameters. From the results, the optimal parameters for machining the geopolymer composites were interpreted

The Influence of Tuff Particles on the Properties of the Sintered Copper Matrix Composite for Application in Resistance Welding Electrodes

This paper presents modern copper-matrix composite materials in which volcanic tuff particles are used as a reinforcing phase. The aim of the research was to determine the optimal shares of volcanic tuff additive based on such criteria as softening temperature, relative density, electrical conductivity, and hardness. The properties of the produced and tested composites allowed us to determine the usefulness of this type of material for resistance welding electrodes. To confirm the assumptions made, preliminary investigations of the durability and behavior of electrodes made of the tested material during the processes of welding non-alloy steel sheets were carried out. As a result of the research, it was discovered that the addition of 5% tuff produces the best results in this type of composite. It was found that for the sample with a 5% share of tuff, a high softening point above 600 °C was obtained, high hardness after densification at the level of 62 HRB, and high relative density of approximately 95% and very good conductivity at the level of approximately 45 MS/m. The conducted tests did not show any electrode wear different from the commonly used alloys for resistance welding

Electric Discharge Machining on Stainless Steel Using a Blend of Copper and Fly Ash as the Electrode Material

In the current work, several composites made with fly ash reinforcements are used to conduct electrical discharge machining (EDM) on stainless steel that is commercially accessible. Four composites were prepared with 2.5 to 10% reinforcement of fly ash with steps of 2.5%, copper is used as the matrix material. The specimens were created using the powder metallurgy method, which involved compaction pressures of 450 MPa and 900 °C for 90 min of sintering. The prepared composites are used as the electrode tool for EDM. EDM studies were carried out at two different current amplitudes (5A and 15A) by maintaining the Pulse on time (100 µs), Pulse off time (50 µs), and the depth of machining as 2 mm. The findings show that the addition of more fly ash to the copper matrix increased the material removal rate when cutting the SS304 plate and had a negative impact on the tool. The composite loses its ability to transfer heat during machining as the level of fly ash increases, raising the temperature in the copper matrix and causing the copper to melt more quickly at the electrode interface during machining, leading to increased electrode wear. While tool life was reduced because of the increase in current amplitude, machinability was enhanced

Trafficking of the Menkes copper transporter ATP7A is regulated by clathrin-, AP-2-, AP-1-, and Rab22-dependent steps

The transporter ATP7A mediates systemic copper absorption and provides cuproenzymes in the trans-Golgi network (TGN) with copper. To regulate metal homeostasis, ATP7A constitutively cycles between the TGN and plasma membrane (PM). ATP7A trafficking to the PM is elevated in response to increased copper load and is reversed when copper concentrations are lowered. Molecular mechanisms underlying this trafficking are poorly understood. We assess the role of clathrin, adaptor complexes, lipid rafts, and Rab22a in an attempt to decipher the regulatory proteins involved in ATP7A cycling. While RNA interference (RNAi)–mediated depletion of caveolin 1/2 or flotillin had no effect on ATP7A localization, clathrin heavy chain depletion or expression of AP180 dominant-negative mutant not only disrupted clathrin-regulated pathways, but also blocked PM-to-TGN internalization of ATP7A. Depletion of the μ subunits of either adaptor protein-2 (AP-2) or AP-1 using RNAi further provides evidence that both clathrin adaptors are important for trafficking of ATP7A from the PM to the TGN. Expression of the GTP-locked Rab22aQ64L mutant caused fragmentation of TGN membrane domains enriched for ATP7A. These appear to be a subdomain of the mammalian TGN, showing only partial overlap with the TGN marker golgin-97. Of importance, ATP7A remained in the Rab22aQ64L-generated structures after copper treatment and washout, suggesting that forward trafficking out of this compartment was blocked. This study provides evidence that multiple membrane-associated factors, including clathrin, AP-2, AP-1, and Rab22, are regulators of ATP7A trafficking