Characterizing the Effect of Processing Parameters on Temperature Distribution of 7075 Aluminum Alloy Slurry Prepared by Enthalpy Control Process

There is a strong demand for high-strength aluminum alloys such as 7075 aluminum alloy to be applied for rheocasting industry. The overriding challenge for the application of 7075 alloy is that its solid fraction is very sensitive to the variation of temperature in the range of 40% ~ 50% solid fraction, which inevitably narrows down the processing window of slurry preparation for rheocasting process. Therefore, in this work, a novel method to prepare semi-solid slurry of the 7075 alloy, so called Enthalpy Control Process (ECP), has been developed to grapple with this issue. In the method, a medium-frequency electromagnetic field was applied on the outside of slurry preparation crucible to reduce the temperature difference throughout the slurry. The effect of processing parameters, including heating power, heating time, the initial temperature of crucible and melt weight, on the temperature field of the semi-solid slurry was investigated. The results exhibited that although the all the processing parameters had a great influence on the average temperature of the slurry, heating time was the main factor affecting the maximum temperature difference of the slurry. The optimum processing parameters during ECP were found to be heating power of 7.5 KW, the initial temperature of crucible of 30 °C ~ 200 °C and melt weight of 2 kg.

Progress of Semi-Solid Processing of Alloys and Composites in China

Following the rapid growth of the automotive and communication industries, components with high quality and low cost are eagerly desired in China. Various technologies have been developed in China to meet the demand, while semi-solid processing (SSP) of alloys and composites is one of the most successfully developed and practically applied technologies. The major SSP applied in China is the rheocasting in terms of the Swirled Enthalpy Equilibration Device (SEED) process. In this review, we start with a brief reviewing some common slurry preparation methods and recent innovations of the SEED process. Subsequently, we describe the general situation and some recent examples of successful development and applications of SSP in China. Lastly, the future directions in SSP of alloys and composites are highlighted in this frontier research field at the end of this review.

An Assessment of the Influence of Dental Porcelain Slurry Preparation on Flexural Strength of Different Feldspathic Porcelains

Chipping remains a big challenge during the clinical application of glass ceramics in dentistry. The fabrication procedure used affects the mechanical properties of dental feldspathic porcelain and is associated with technical failures. This study aimed to compare the effect of the use of manufacturers’ liquids versus H2O on the flexural strength of glass ceramics. Specimens (n = 120, n = 15 per group) (25 × 4 × 1.2 mm) were obtained using four porcelain powders (Creation CC, IPS InLine, Noritake EX-3, and Vita VM 13). Four groups were produced using porcelain powder and modeling liquid, and four groups using distilled water. The specimens were fired, sintered, and polished. Flexural strength was measured using a universal testing machine. Statistical analyses were conducted using post hoc Tukey’s, two-way ANOVA, and Weibull analysis. Flexural strength values (mean ± SD) of the ceramic-manufacturer’s liquid mixture ranged between 67.2 ± 10.2 and 85.8 ± 12.8 MPA (NR < VT < IV < CR), while flexural strength values of the ceramic–water mixture were between 72.2 ± 6.9 and 95.2 ± 12 MPA (CR < NR < VT < IV). While the choice of the ceramic type significantly affected flexural strength, the use of water vs. manufacturers’ liquid showed in almost all cases no significance. To achieve better flexural strength results, InLine should be used with distilled water mixtures, while all ceramic powders except for Noritake can be used with the manufacturer’s liquid mixtures.

Experimental Study of Hydraulic Sealability and Shear Bond Strength of Cementitious Barrier Materials

In this experimental study, two different cementitious materials including (i) a class of expansive cement that is currently used for P&A operations, and (ii) a non-cement-based naturally occurring rock, known as geopolymer are selected to examine the hydraulic bond strength and shear bond strength. Clean machined steel and rusty corroded steel were selected to represent the casing. The test samples were cured at 90 °C, which is considered as bottom-hole static temperature (BHST), and under elevated pressure of 17.2 MPa for one week. The hydraulic sealability of the barrier materials tested up to 3.4 MPa of differential pressure. The results indicated that additives used in slurry preparation have an impact on the hydraulic sealability of the material. Additionally, the rusty corroded streel provided a better hydraulic sealability comparing to the clean machined steel for the same cementitious material. The shear bond strength test was performed by running the push-out test. According to the present test observations, no correlation was found between the shear bond and hydraulic bond strength of different barrier materials. The geopolymer showed the lowest shear bond strength, while it provided the highest hydraulic sealability.

The Influence of Glass Fiber and Milled Glass Fiber on the Performance of Iraqi Oil Well Cement

The reinforced fiberglass in cement slurry reflects the effect on its properties compared to usual additives. Fiberglass is typically used in cement slurry design for one or another of the following goals: (Earth earthquake, bearing storage, and with differential stresses, to enhance cement durability and increase its compressive strength). The main goal is to use glass fiber and ground fiberglass to improve the tensile strength and moderate compressive strength significantly. On the other hand, the use of glass fibers led to a slight increase in the value of thickening time, which is a desirable effect. Eleven glass fiber samples and milled glass fiber were used to show these materials' effect on Iraqi cement with (0.125, 0.25, 0.5, 0.75, 1, and 2) % of cement weight. Those tests used to study cement slurry‟s following properties were compressive strength, thickening time, rheology properties of free water, filtering, and density. These evaluations showed that slurries with less than 1% fiber content gave a higher compressive strength than a sample containing more than 1% glass fiber. However, the slurry mixed with equal or less than 1% milled glass fiber is higher compressive than the sample mixed with more than 1% milled glass fiber. So the optimal concentration for glass fiber is less than 1% by weight of cement (BWOC); either for milled glass fiber, it is less or equal to 1% BWOC. Both materials contributed to increasing the compressive strength of the cement. However, attention must be paid to the idealThis work is licensed under a Creative Commons Attribution 4.0 International License. concentration that should be added during the cement slurry preparation because if we use these two materials carelessly for the ideal concentration, this leads to the collapse and bombardment of the resistance of the cement rock. In other words, the collapse of cement resistance and causing problems during the cementing process.

Experimental Study of Hydraulic Sealability and Shear Bond Strength of Cementitious Barrier Materials

In this experimental study, two different cementitious materials including (i) a class of expansive cement currently used for plug and abandonment (P&A) operations, and (ii) a non-cement-based naturally occurring rock, known as geopolymer are selected to examine the hydraulic bond strength and shear bond strength. Clean machined steel and rusty corroded steel were selected to represent the casing. The test samples were cured at 90 °C considered as bottom-hole static temperature (BHST) and under elevated pressure of 17.2 MPa for one week. The hydraulic sealability of the barrier materials tested up to 3.4 MPa of differential pressure. The results indicated that additives used in slurry preparation impact the hydraulic sealability of the material. Additionally, the rusty corroded streel provided a better hydraulic sealability comparing to the clean machined steel for the same cementitious material. The shear bond strength test was performed by running the push-out test. According to the present test observations, no correlation was found between the shear bond and hydraulic bond strength of different barrier materials. The geopolymer showed the lowest shear bond strength, while it provided the highest hydraulic sealability.

Synthesis of a novel amphoteric copolymer and its application as a dispersant for coal water slurry preparation

In this work, a novel amphoteric copolymer named Poly(sodium p-styrenesulfonate– co -acrylic acid- co -diallyldimethylammonium chloride) (P(SS- co -AA- co -DMDAAC)) was synthesized via free radical polymerization. Afterwards, P(SS- co -AA- co -DMDAAC) was explored for use as a dispersant in coal water slurry (CWS) preparation. The structure of P(SS- co -AA- co -DMDAAC) was verified by Fourier transform infrared spectroscopy and nuclear magnetic resonance. The synthetic conditions were optimized as the feed ratio of AA to SS was 1 : 1 (for Yulin coal) or 1.5 : 1 (for Yili coal), and DMDAAC dosage was 4.0 wt% (for Yulin coal) and 6.0 wt% (for Yili coal) toward total monomers. The performances of P(SS- co -AA- co -DMDAAC) as a dispersant for CWS were evaluated by various technologies, such as apparent viscosity, zeta potential, static stability and contact angle measurements. The results revealed that the optimized dosage of P(SS- co -AA- co -DMDAAC) in CWS preparation was 0.3 and 0.4 wt% for Yulin coal and Yili coal respectively. In this optimum condition, CWS prepared using P(SS- co -AA- co -DMDAAC) as dispersant showed a typical shear thinning behaviour and excellent stability, which are desired in industries. The rheological models also confirmed the pseudo-plastic characteristics of CWS. Finally, compared with the widely used anionic dispersant naphthalene sulphonate formaldehyde condensate (NSF) and poly(sodium p-styrenesulfonate) (PSS), P(SS- co -AA- co -DMDAAC) developed in this work exhibited better slurry making performance. The introduction of cationic functional groups promoted the adsorption of the dispersant, which further enhanced the electrostatic repulsion and steric hindrance among coal particles. Accordingly, the viscosity of CWS decreased and static stability enhanced.