Cold Isostatic Pressing Research Articles

Influence of ZrO2 on the phase composition and mechano-physical properties of MgO–ZrO2 refractories prepared by cold isostatic pressing

MgO–ZrO2 refractories were produced by combining MgO refractories (with a CaO/SiO2 ratio of 2.1) with monoclinic ZrO2 powder using wet-bag cold isostatic pressing. The phase composition and mechano-physical properties of the MgO–ZrO2 materials were influenced by the interaction between ZrO2 and MgO refractories. ZrO2 enhanced the cold modulus of fracture of MgO refractories but decreased the hot modulus of fracture due to changes in bonding phases. The addition of 1 wt% ZrO2 transformed Ca2SiO4 into CaMgSiO4 and CaZrO3. CaMgSiO4 with a low melting point deteriorated the hot modulus of fracture of MgO–ZrO2 refractories from 13.3 to 2.97 MPa. With an increase in ZrO2 to 3–5 wt.%, CaMgSiO4 remained while CaZrO3 gradually transformed into the solid-solution Ca0.2Zr0.8O1.8. This transformation occurred because ZrO2 seized CaO from CaZrO3 to stabilize itself. Based on thermodynamic equilibrium ZrO2 preferentially reacts with CaO-containing phases in the MgO matrix in the following order: Ca3SiO5 > Ca2SiO4 > CaZrO3 > CaMgSiO4. The thermal shock resistance of MgO–ZrO2 refractories with less than 5 wt% ZrO2 was not significantly improved by assessing their strength loss and coefficient of thermal expansion. In conclusion, it is recommended to incorporate ZrO2 into MgO refractories with low SiO2 or CaO to develop high-performance MgO–ZrO2 refractories.

Performance comparison analysis of cold isostatic pressing and vibrational method for reactive powder concrete

The low water-cement ratio has a significant effect on increasing the compacted density of the concrete, thereby enhancing its mechanical properties and microstructures. This paper introduces an innovative approach of utilizing the cold isostatic pressing method to prepare reactive powder concrete (RPC) specimens with an ultra-low water-cement ratio which not exceeds 0.16. And it is compared with the specimens prepared by the traditional vibrational method which conversely requires the minimum water-cement ratio of 0.21. The results show that the RPC specimens under cold isostatic pressing exhibit enhanced compressive strength and microhardness, as well as improved matrix compactness. Conversely, the RPC matrix produced under the vibrational method not only contains a small number of air-entrained bubbles that can influence the strength of matrix but also exhibits a significantly larger cumulative volume of harmful pores that affect the performance of RPC compared to cold isostatic pressing. Therefore, cold isostatic pressing technology based on all-directional hydroforming is a powerful tool for the preparation of high-strength RPC, which significantly reduces the internal defects of the specimen, and the prepared RPC has superior mechanical properties and matrix structure.

Apatite–Wollastonite (AW) glass ceramic doped with B2O3: Synthesis, structure, SEM, hardness, XRD, and neutron/charged particle attenuation properties

In the study, the influence of doping apatite-wollastonite (AW) glass-ceramics (GCs) with B2O3 on the structural, physical, microstructural, and light and heavy particle interaction properties is presented. Using the solid-state reaction and the cold isostatic press method, pristine AW, 10 wt% (AW-B10), and 20 wt% (AW-B20) B2O3-doped AW GCs were prepared. The prepared GCs were subject to structural, chemical compositional, and surface morphological investigation through standard experimental processes. Furthermore, the neutron (fast and thermal) and charged radiation (electron, proton, alpha, and carbon ion) interactional parameters of the GCs were obtained through standard theoretical models and software. The density of AW (2.91 gcm−3) increases to about 2.957 and 2.986 gcm−3 as B2O3 increases to 10 and 20 wt%, respectively. The presence of boron oxide supported the wollastonite phase to remain glass and suppressed crystallisation in the AW GCs. Doping AW with B2O3 improved the interaction probabilities of the GCs with fast and thermal neutrons, electrons, protons, alpha particles, and carbon ions. B-rich AW is thus potentially useful as a target material in human tissues for boron neutron capture therapy for the management of cancer and tumours, isolating or shielding specific tissues in ion beam therapy processes, and other techniques that require the exposure of human tissues to irradiation.

Shaping techniques' influence on the electrochemical properties of BaCe0.6Zr0.3Y0.1O3-δ proton conductor

Hydrogen's significance as a clean and high-energy source spans various industries, driving advancements in fuel cell technology, transportation, and renewable energy storage systems. In particular, solid-state proton conductors like perovskite-type materials exhibit promising attributes for applications such as fuel cells and hydrogen sensors. However, conventional shaping techniques like uniaxial pressing impose limitations on device scalability and geometry. To address these challenges, alternative methods are gaining traction, like cold isostatic pressing or additive manufacturing. Each technique offers distinct advantages in shaping materials, impacting their structural and morphological properties. In this study, pellets of BaCe0.6Zr0.3Y0.1O3-δ (BCZY) solid-state electrolyte were fabricated using four different shaping techniques: uniaxial pressing, cold isostatic pressing, 3D extrusion, and lithography. Characterization via X-ray diffraction, scanning electron microscopy, and electrochemical impedance spectroscopy provided insights into changes in crystalline structure, sintering quality, and electrochemical properties, respectively.

Effect of Cold Isostatic Pressing and VC Grain Growth Inhibitor Addition on WC Grain Size and Mechanical Properties of WC-8Co Cemented Carbide

In this study, sub-micron WC-Co cemented carbides were fabricated by cold isostatic pressing using recycled WC powder, Co powder, and VC grain growth inhibitor as the initial composite powders. The raw WC-8Co and WC-8Co-0.3VC compositions were prepared according to conventional technology. After that, part of the green compacts was CIP-ed under pressure of 200 MPa. Sintering was carried out in an industrial vacuum sintering furnace at a temperature of 1420 ºC simultaneously for all samples. The microstructures and properties, including density, coercivity, transverse rupture strength, A-type Rockwell hardness and fracture toughness were investigated, characterized and compared systematically. The experimental results showed that the action of cold isostatic pressing in combination with grain growth inhibitor addition promoted ultrafine grains with the finest WC grain size of 0.68 μm and an increase in the fracture toughness up to 15.4 MPa·m1/2 ± 0.2 compared to rest cemented carbides, showing the techniquehas potential to fabricate cermets with both small average WC grain size and high fracture toughness, which is key in providing excellent performance.

Phase purifying and dielectric improvement in Zn2SiO4 ceramics via simply controlling the particle size of SiO2

AbstractThe zinc orthosilicate, Zn2SiO4 ceramics, exhibit great potential as microwave dielectric materials due to their low dielectric constant and ultrahigh quality factor. The solid‐state synthesis of Zn2SiO4 ceramics often results in the presence of a secondary phase of ZnO, however, leading to significantly lower Q×f values. Cold‐isostatic‐pressing (CIP) and nonstoichiometry have been proven effective in purifying the Zn2SiO4 but need elaborate process and composition manipulation. In this work, it was found that the particle size of SiO2 plays a crucial role in purifying the Zn2SiO4 phase. Specially, nano‐sized SiO2 particles (15 and 30 nm) led to the formation of a ZnO secondary phase in synthesized Zn2SiO4 ceramics, while micro‐sized (2 and 10 µm) resulted in pure‐phase Zn2SiO4 with excellent microwave properties. Notably, when prepared with 10 µm SiO2 and sintered at 1 340°C, the resulting Zn2SiO4 exhibited outstanding microwave performances with a Q×f value of 122 570 GHz, a temperature coefficient of frequency τf of −51.9 ppm/°C, and a dielectric constant (εr) of 6.5. These findings highlight the importance of controlling particle size during synthesis to achieve desired material properties such as purity and excellent microwave performances.

The Influence of the Green Density on the Quality of ZTA Zirconia Toughened Alumina Plungers

The purpose of this study is to investigate the effect of the green density (ρ<sub>g</sub>) on the sintered density (ρ<sub>s</sub>), shrinkage according height and diameter (HS, DS), relative density, porosity and hardness of ZTA ceramic plungers. Zirconia toughened alumina is characterized by excellent properties of hardness, toughness, thermal and chemical resistance, which make composite material interesting for multiple applications. Some of the significant applications of ZTA ceramics are in the production of biomedical implants, cutting tools, parts for pumps and others. The material is composed of high purity alumina 90% and 10% of zirconium oxide. This material successfully compensate fragility of the alumina and zirconium oxide price. After 24 hours of milling in a ball mill (Dorst, Germany) slurry with a specific surface 25 832 cm2/g was transferred into a mixer with addition of binders (PVA + soap based binder) through a vibrating sieve (British and Foreign Patents). Solid content (%) of the slurry in amount of 69.16 was confirmed by thermogravimetric and differential gravimetric analyzes. The 1000 kg of the powder dried by spray drying (Spray dryer Niro) contains 2.6% of binders and 0.2% of moisture. Three sets of plungers with outer diameter of 3.6 cm, inner diameter of 2.0 cm and height of 7.6 cm were produced by cold isostatic pressing (CIP) using different pressures. The first set marked as 'A' was pressed by pressure of 80 MPa, the second set marked as 'B' was pressed by pressure of 100 MPa, and third set marked as 'C', was pressed by pressure of 150 MPa. According to statistical data processing, comparison and analysis of the results it is concluded that the quality of the ZTA plungers, in specific presented case, significantly depends on the green density (ρ<sub>g</sub>).

Physically‐Deposited Hole Transporters in Perovskite PV: NiOx Improved with Li/Mg Doping

AbstractNickel oxide (NiOx) has received a lot of attention as an inorganic hole transport material (HTM) in perovskite solar cells (PSCs) during the last decade, owing to its high hole mobility, chemical stability, good optical transparency, and suitable energy levels that align with the valance band of the perovskite absorber methylammonium lead iodide (MAPbI3). This study explores Li and Mg co‐doped NiOx thin films physically‐deposited from developed sputtering targets obtained through cold isostatic pressing and sintering. After sputtering, the structural, elemental, morphological, optical, and electrical properties of the layers are investigated by XRD, XPS, SEM, AFM, UV–vis spectrophotometer, and Hall‐effect; revealing that crystalline, homogeneous, and smooth films are obtained. In particular, improvements in mobility and conductivity values are observed with Li and Mg doping, which contribute to enhanced PSC performance when used as an HTM layer in the glass‐indium tin oxide (ITO)/NiOx‐based HTM/MAPbI3/phenyl butryic acid methyl ester (PCBM)/bathocuproine (BCP)/Ag architecture. The champion solar cell achieves PCE of 15.52%. In addition, the average values of all samples are boosted, JSC (from 13.21 to 15.60 mA cm−2) and FF (from 59.32% to 67.7%), relative to pristine HTM, resulting in a pronounced PCE increment of up to 30% with the HTM film sputtered by a single target of co‐doped material.

Large area hole defect repair of titanium alloys by powder pressing and vacuum sintering

A simple and efficient powder metallurgy method to repair the large area hole defect of titanium alloys was addressed in this work. The titanium-based powder mixture was pressed in the defect area by cold isostatic pressing and then sintered at elevated temperature. Three powder systems Ti–Ni/Ti–Sn/Ti–Ni–Sn were chosen according to liquid phase sintering theory. Ti–7Ni–5Sn powder system led to better densification and interface bonding by sintering at 1200 °C. After repair, the strength reached more than 95 % that of the Ti–6Al–4V matrix.

Virtues of Cold Isostatic Pressing for Preparation of All-Solid-State-Batteries with Poly(Ethylene Oxide).

All-solid-state-batteries (ASSBs) necessitate the preparation of a solid electrolyte and an electrode couple with individually dense and compact structures with superior interfacial contact to minimize overall cell resistance. A conventional preparation method of solid polymer electrolyte (SPE) with polyethylene-oxide (PEO) generally consists in employing uni-axial hot press (HP) to densify SPE. However, while uni-axial press with moderate pressure effectively densifies PEO with Li salts, excessive pressure also unavoidably results in perpendicular elongation and deformation for polymer matrix. In this research, to overcome this limitation for the uni-axial press technique, a cold isostatic press (CIP) is applied to the fabrication of ASSB with PEO and LiFePO4 . CIP effectively and uniformly applies pressure as high as 500 MPa without deformation. Characterizations confirm that CIP treated SPE has enhanced mechanical puncture strength, increasing from 499.3±22.6 to 539.3±22.6 g, and ionic conductivity, increasing from 1.04×10-4 to 1.91×10-4 S cm-1 at 50 °C. ASSB treated by CIP demonstrates remarkably enhanced rate capability and cyclability compared with the cell processed by HP, which is further evidenced by improvement of the apparent Li ion diffusion constant based on Sand equation analysis. The improvement enabled by CIP treatment originates from the superior interface uniformity between electrodes and SPE and from the densification of the LiFePO4 and SPE composite electrode.

Consolidation of water-atomized chromium–nickel-alloyed powder metallurgy steel through novel processing routes

When processing powder metallurgy (PM) steels, the conventional press and sinter route can reach a relative density up to 95%, which is insufficient for applications when dynamic mechanical performance is critical. In this study, a novel route is demonstrated consisting of cold isostatic pressing (CIP) followed by sintering and capsule-free hot isostatic pressing (HIP), allowing to achieve full density PM steels. Water-atomized steel powder admixed with 2 wt.% Ni was subjected to CIP and followed by sintering in 90N2/10H2 atmosphere at 1120 and 1250°C, and in vacuum (10−2 mbar) at 1250 and 1350°C, respectively. At the highest explored CIP pressure of 600 MPa, the three high-temperature sintering runs at 1250°C in 90N2/10H2 atmosphere and vacuum, and 1350°C in vacuum resulted in relative density of ∼94% and closed surface pores. This condition with necessary closed porosity then allowed subsequent capsule-free HIP after sintering, resulting in full densification of the components.

Effect of Microstructural Change under Pressure during Isostatic Pressing on Mechanical and Electrical Properties of Isotropic Carbon Blocks.

In this study, carbon blocks were fabricated using isotropic coke and coal tar pitch as raw materials, with a variation in pressure during cold isostatic pressing (CIP). The CIP pressure was set to 50, 100, 150, and 200 MPa, and the effect of the CIP pressure on the mechanical and electrical properties of the resulting carbon blocks was analyzed. Microstructural observations confirmed that, after the kneading, the surface of isotropic coke was covered with the pitch components. Subsequently, after the CIP, granules, which were larger than isotropic coke and the kneaded particles, were observed. The formation of these granules was attributed to the coalescence of kneaded particles under the applied pressing pressure. This granule formation was accompanied by the development of pores, some remaining within the granules, while others were extruded, thereby existing externally. The increase in the applied pressing pressure facilitated the formation of granules, and this microstructural development contributed to enhanced mechanical and electrical properties. At a pressing pressure of 100 MPa, the maximum flexural strength was achieved at 33.3 MPa, and the minimum electrical resistivity was reached at 60.1 μΩm. The higher the pressing pressure, the larger the size of the granules. Pores around the granules tended to connect and grow larger, forming crack-like structures. This microstructural change led to degraded mechanical and electrical properties. The isotropic ratio of the carbon blocks obtained in this study was estimated based on the coefficient of thermal expansion (CTE). The results confirmed that all carbon blocks obtained proved to be isotropic. In this study, a specimen type named CIP-100 exhibited the best performance in every aspect as an isotropic carbon block.

Global and Local Deformation Analysis of Mg-SiC Nanocomposites: Digital Image Correlation (DIC) and Representative Volume Element (RVE) Techniques

Improving the ductile deformation behavior of Mg-SiC nanocomposites without compromising strength is critical to enhancing their mechanical properties. Mg-SiC nanocomposites are produced through mechanical milling, cold isostatic pressing, sintering, and hot extrusion processes. This study investigates the uniaxial stress–strain response and deformation behavior of the Mg-SiC nanocomposite compared to pure Mg samples with and without the milling process. The deformation behavior was investigated by two-dimensional (2D) digital image correlation (DIC) at two macroscopic and microscopic scales, employing light micrographs and in situ loading samples, respectively, in the scanning electron microscope. Compared to the pure Mg samples, the mechanical test results demonstrated a significant improvement in strength (80 MPa) and fracture strain (23.5%) of the Mg-SiC nanocomposite. The three-dimensional (3D) representative volume element (RVE) model revealed the particle dispersion effect on the mechanical properties of the nanocomposite. The RVE results demonstrate ductile deformation behavior in the sample with homogenous dispersion of SiC particles compared with the heterogeneous dispersion of SiC particles in Mg-SiC nanocomposite. The results demonstrated a good agreement between DIC and RVE predictions for Mg-SiC nanocomposites across macro- and microscales.

Pressureless sintering of large sized fully ceramic microencapsulated fuel pellets

Large-sized fully ceramic microencapsulated (FCM) nuclear fuel pellets were fabricated by a novel tape casting process in this study. The process involved producing a single layer of FCM fuel green tapes embracing TRISO particles by tape casting with silicon carbide ceramic as the matrix. The resulting tapes were stacked vertically and made into green bodies through cold isostatic pressing. Large-sized FCM fuel pellet with diameters over 86 mm was then successfully prepared by pressure-less sintering with AlN-Y2O3-Sc2O3−MgO as sintering additives. The FCM fuel pellets obtained through this method exhibited a dense structure, flat surface, and no cracks. Thus, the integrated formation of the fuel-free zone and fuel-filled zone could be realized by precisely controlling the fuel-free zone thickness. The TRISO particles were regularly and uniformly distributed in a triangular shape and remained structurally intact. By adjusting the spacing of the TRISO particles in the FCM fuel pellets to a range of 500 to 1500 μm, the volume fraction of fuel particles in the FCM fuels was controlled between 12.8 and 31.7 vol.%.

Production of an eco-friendly, effective antimicrobial and antifungal from cerium/natural bio-hydroxyapatite coating for titanium plates suitable for bone augmentation

As a promising technique for rebuilding bone defects, materials having enhanced osteoductivity and antimicrobial and fungi effects have been used for bone replacement. Accordingly, the present study aims to develop a sintered titanium (Ti) plate prepared by the cold isostatic press (CIP) coated with nano bio-natural hydroxyapatite (n-HA) via freeze-drying technique for bone substitution. Moreover, the influence of cerium chloride heptahydrate doping with different concentrations of 0.5, 2, and 8 wt% was evaluated for enhancing the osteogeneration process and antibacterial activity on titanium (Ti) plates instead of antibiotic-loaded. Physical properties showed that the n-HA/2%CeCl3 coat is the most suitable concentration with an appropriate porosity of 73.43 ± 3.52 compared to porous n-HA coating Ti plate with a porosity of 90.38 ± 0.27. The biological activity (in-vitro) study in terms of following up the apatite nucleation on the blank Ti plate and Ti/n-HA/2 % CeCl3 surfaces after immersions in SBF for up to 28 days showed the formation of spherical clusters from carbonated apatite particles on the sample's surface, with a Ca/P ratio equal to 2.26. The cytotoxicity test was examined using a bone osteosarcoma cell line (HOS). The final results confirmed minimal cytotoxicity for the plate coated with n-HA/2 % CeCl3 (3.6 %). Cell attachment results indicate the potential of the cells to adhere and spread on the surface. In addition, the antimicrobial assessment of n-HA/2 % CeCl3 coated Ti plates showed broad-spectrum activity against not only the gram-positive or gram-negative but also fungal ones.

Synthesis, microstructure and thermophysical properties of (La0.2Y0.2Sm0.2Eu0.2Gd0.2)2Zr2O7 high-entropy oxide ceramic

In this study, a dense high-entropy oxide ceramic (La0.2Y0.2Sm0.2Eu0.2Gd0.2)2Zr2O7 with a relative density of 93.7 %RD was synthesized by cold isostatic pressing, coupled with the pressureless sintering method. The microstructure and physical properties were characterized systematically, revealing an intrinsic hardness of 7.9 GPa and flexural strength of 187.9 MPa. Moreover, the elastic and shear moduli decreased from 148.05 to 56.68 GPa at 25 °C to 117.44 and 44.63 GPa at 1200 °C, respectively. The thermal diffusivity in the temperature range of 25–1200 °C decreased from 0.0053 to 0.0041 cm3/s, and the thermal expansion coefficient was 11.0 × 10−6 K−1. The excellent thermal insulation performance of the high-entropy oxide ceramic (La0.2Y0.2Sm0.2Eu0.2Gd0.2)2Zr2O7 and its similar thermal expansion coefficient to those of Ni-based superalloys demonstrate that the material has broad application prospects in the field of thermal barrier coatings.

Microstructure and high-temperature deformation performance of liquid-dispersed evaporated Nano-ZrTiO4 doping molybdenum alloy

To enhance the low-temperature plasticity and high-temperature strength of molybdenum alloys, we introduce a method of uniformly dispersing nano-ZrTiO4 particles within and between molybdenum grains. This approach effectively eliminates the formation of hard agglomerations between particles and leads to a further refinement of molybdenum grains. The research employs molecular level solid-liquid doping and subsequent liquid dispersion evaporation techniques to successfully synthesize Mo-ZrTiO4 nano-composite powder following H2 reduction. Subsequently, a novel fine-grained Mo-ZrTiO4 alloy sintered billet is successfully fabricated through cold isostatic pressing and high-temperature sintering. To assess the efficacy of the process, three sets of comparative experiments are designed, each employing different methods. The comparative studies have revealed compelling advantages of the liquid dispersed evaporated fine-grained samples of Mo-ZrTiO4. The key advantages identified are as follows:the samples demonstrate a refined grain size, ranging from 2 μm to 4 μm. Within the samples, the nano ZrTiO4 particles have an average size of approximately 200 nm. The density and Vickers hardness of the samples is measured at 10.21 g/cm3 and 268.5 ± 17HV0.2, respectively. The samples exhibit impressive toughness even at room temperature, notably, the high-temperature compressive strength of these samples surpasses that of the deformed samples reported in previous literature concerning this system. The mechanism of liquid dispersion evaporation method in grain nucleation, growth, and powder drying, reduction, and sintering processes was systematically elaborated. Simultaneously, a detailed analysis was conducted on two high-temperature strengthening mechanisms that impact the mechanical properties. The results indicate that this excellent performance can be attributed to the synergistic effect of both fine grain strengthening and uniform dispersion strengthening of second-phase nanoparticles.

Physical, microstructural, and radiation energy absorption properties of recycled CRT-screen glass doped with Bi2O3

In this study, pristine TV-CRT screen glass (TVS) and those doped with 10% (TVS-Bi10) and 20% (TVS-Bi20) by weight of Bi2O3 were prepared and analyzed for their physical, microstructural, radiation dosimetry quantities, and shielding features. The glass samples were fabricated using the cold isostatic press method. The surface microstructure and the chemical composition of the glass ceramics were probed with the aid of the scanning electron microscopy-energy dispersive X-ray (SEM-EDX) system. Photon absorption and scattering quantities were estimated using standard procedures. The mean density values determined by Archimedes principle were calculated as 2.614, 2.788, and 3.056 gr/cm3 for the TVS, TVS-Bi10, and TVS-Bi20 samples, respectively. SEM images of samples showed that the increase in bismuth content increased sample crystallization and surface pores. The estimated mass energy absorption coefficients of the samples varied from 0.0177 to 11.7578 cm2/g for TVS, 0.0182–14.5218 cm2/g for TVS-Bi10, and 0.0187–17.7615 cm2/g for TVS-Bi20 for photon energies between 15 keV and 15 MeV. At 1 mm glass thickness and for 100 keV gamma rays, the dose rate was 13 MR/h, 17 MR/h, and 22 MR/h for TVS, TVS-Bi10, and TVS-Bi20, respectively. The mass stopping powers of electrons at 15 keV have values of 12.37 MeV cm2/g 12.21 MeV cm2/g, and 12.03 MeV cm2/g for TVS, TVS-Bi10, and TVS-Bi20, respectively. Generally, the ranges of the CPs were such that those of TVS > TVS-Bi10>TVS-Bi20. Bi2O3 increases the electron, proton, alpha particle, and carbon ion absorbing features of the TVS-BiX samples. Bi2O3 suppresses photon scattering, makes the TVS glass more sensitive to photon and charged particle interaction and absorption. The investigated glasses are useful for gamma-radiation, light, and heavy ion absorption and protection technology.

Cold isostatic pressing-study on methane production and microbial communities in anaerobic digestion of wheat straw with high-solids

In this study, the effect of cold isostatic pressing (CIP) pretreatment on the physicochemical properties and subsequent anaerobic digestion (AD) performance of wheat straw (WS) was explored, which did not have additional chemical reagent over the whole process. The WS was subjected to CIP pretreatment by pressures from 350 to 700 MPa, respectively, while AD was carried out at mesophilic temperature with total solids (TS) 7% and 14%. The mapping indicated that the CIP pretreatment promoted the hydrolysis of WS by destroying the dense structure. The CIP pretreatment changed pH and volatile fatty acids (VFAs) in the AD system. Compared with the control group, the cumulative methane production of CIP pretreatment group with TS 14% increased by 22.07%–56.18%. The acetic acid concentration peaked on 4th day and 14th day with 3943.23 mg/L and 3815.21 mg/L, respectively, in H600, and propionic acid concentration also reached two peaks at the same time with 2014.92 mg/L and 2405.20 mg/L, respectively. It was also observed that the CIP pretreatment maintained the pH in the range of 6.44–7.40, maintaining the stability of the overall system. It was also found that CIP pretreatment increased 9 species of hydrolysis and acidogenic bacteria, and methanogen Methanosarcina, thereby facilitating the hydrolysis and methanogenic stages. Predictive functional profiling comfirmed that CIP pretreatment could promote glycolysis/gluconeogenesis, fatty acid metabolism, and fatty acid degradation, whose relative abundance increased from 1.10% to 1.13%, 0.60%–0.62%, and 0.19%–0.23%. Methanogenic capacity of the system was improved because of CIP pretreatment enhancing the accessibility of microorganisms by disrupting the microstructure of WS. The energy conversion analysis showed that this method without chemical reagent addition is feasible for high-solids anaerobic digestion.

Structural and electrical properties of PLZT x/65/35 ceramics prepared via mechanical activation method near the morphotropic phase boundary

This paper reports the effect of lanthanum addition on the structural and electrical properties of (Pb1-xLax)(Zr0.65Ti0.35)O3 (PLZT x/65/35, x = 8%,10%,12%,15%) ceramics near the morphotropic phase boundary. Studies were conducted on the PLZT x/65/35 ceramics synthesized via a combinatorial approach of high-energy ball milling (mechanical activation method) followed by Cold Isostatic Pressing (CIP). Due to the application of CIP, PLZT ceramics exhibited improved density and a closely packed microstructure. The SEM analysis showed that PLZT x/65/35 ceramics exhibited an increase in grain size with higher concentrations of La3+ ions. Room temperature X-ray diffraction results revealed the formation of perovskite PLZT phase. The investigation on temperature-dependent dielectric, ferroelectric properties of PLZT x/65/35 ceramics provided experimental confirmation of structures cited in XRD analysis. Among all the compositions, PLZT 8/65/35 samples showed a well saturated, uniform P–E hysteresis loop with a high remanent polarization (Pr). Poled PLZT 8/65/35 samples displayed electric field induced large strains with limited hysteresis. Piezoelectric charge coefficients (d33), electromechanical coupling factors (kp, k33, k31) were determined for poled PLZT x/65/35 ceramics and it was found that PLZT 8/65/35 ceramics reveal properties superior to other compositions. Furthermore, the unipolar strain, Pr, d33, kp, k33, k31 values of PLZT 8/65/35 composition exceeded the previously reported ones for the same composition prepared via sol-gel synthesis technique.