•Zein promoted the aggregation of KGM chains in KGM/zein blend solution.•Zein particles grew larger but were homogeneously distributed during drying.•KGM/zein blend solution gradually formed a weak ...gel after 2 h of drying at 60 °C.
During film formation at 60 °C, the microstructure and rheological properties of konjac glucomannan (KGM) film-forming solution and KGM/zein blend film-forming solution were investigated. The drying process of film-forming solutions was divided into two stages according to the drying curves. Scanning electron microscopy showed that KGM chains in the blend solution aggregated into thicker chains and formed a molecular network with larger pores. Zein particles grew larger but were homogeneously distributed during drying as observed by confocal laser scanning microscopy. The addition of zein improved the thermal stability of the film-forming solution. As the drying proceeded (up to 8 h), KGM solution exhibited a typical concentrated solution behavior due to molecular entanglement; whereas the blend solution gradually formed a weak gel after 2 h. Complex viscosity data for the film-forming solutions were well-fitted by the power-law model. The information obtained from the study is important for understanding the film-forming mechanism.
Metal forming process is one of the most important manufacturing processes that translate the sheet and bulk metal to the final product with simple punch and. Single point incremental forming (SPIF) ...process is considered as a modern flexible manufacturing techniques that is use a simple tool and non-specific fixture die to complete the forming, this method is used in prototype manufacturing system due to the time consuming during the forming. The advantage of this process is low cost and simple equipment. However, some limitation was founded including poor geometric accuracy, non- uniform thickness distribution, dimple and high forming time. Multi-point forming (MPF) is another modern forming method that is used in industrial applications due to its advantage such as uniform thickness distribution with low forming time consuming. This method used matrix of simple tools to deform the sheet metal to the desired shape. Wrinkle and dimple due to small contact area between tool and blank under high forming force are considered the main limitation of using MPF process. To take the advantages of this processes with reduced the limitations a hybrid forming (HF) process of both MPF and SPIF are used. The experimental work was applied to produce a hemi-spherical product of brass blank using the SPIF, MPF, and HF processes. Satisfactory results are obtained using a hybrid forming process with free of defects products and reduction in production as compared to the SPIF. A high improve in microstructure including refinements in grain size with twins effects. The sample produced with SPIF process showed a high microhardness as compared to the sample produced using MPF process, however, the hybrid MPF and SPIF forming process showed slightly improving in microhardness as comparing to the as received materials, reflecting the microstructure development of the processed samples.
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•Temperature, fO2, and compositions of fluids control trace element occurrence in sulfides.•Gold occurrence is invisible as solid solution and visible as micron-sized ...electrum.•Incorporation mechanisms of invisible gold are different by structurally bound gold.•Prolonged interaction generates Cu (–Au) mineralization in IOCG-like deposits.
Gold (e.g., electrum) has been reported in the Paleozoic Heijianshan Fe–Cu (–Au) or iron oxide–copper–gold-like (IOCG-like) deposit in the Eastern Tianshan, but relationships between gold occurrence and sulfides are unclear. The Heijianshan Fe–Cu (–Au) (or IOCG-like) deposit underwent five alteration and mineralization stages: Pre-ore epidote alteration (Stage I), syn-ore magnetite/iron mineralization (Stage II) followed by pyrite alteration (Stage III) and Cu (–Au) mineralization (Stage IV), and post-ore late veins (Stage V). This deposit mainly has two types of pyrite (A and B) based on pyrite–hematite and pyrite–pyrrhotite–chalcopyrite assemblages. They are euhedral to subhedral and mainly homogenous, with the former having porous or inclusion-rich domains. Trace elements incorporating into pyrite at Heijianshan are mainly controlled by compositions (e.g., As, Co, and Cu), temperature (e.g., Ni and Se), and oxygen fugacity (fO2; e.g., As and Se) of hydrothermal fluids, respectively. The time-resolved depth-concentration profiles suggest trace elements in pyrite and chalcopyrite occur as solid solution (e.g., Co, Ni, Zn, As, and Se) and micro- to nano-sized mineral inclusions (e.g., Cu, Bi, and Pb). The gold occurrence at Heijianshan is invisible as solid solution in Stage III pyrite and Stage IV chalcopyrite and visible as micron-sized Stage IV electrum. Moreover, incorporation mechanisms of invisible gold are Au3+ substituting iron or copper in pyrite A and chalcopyrite, respectively, and Au+ incorporating into the vacancy or defect positions of pyrite B. Sulfides texture and geochemical compositions when combined with previous in-situ sulfur isotope suggest that pyrite formation was resulted from interaction between external basinal brines and altered host rocks under different temperature and fO2 conditions. Ongoing fluid-rock reaction led to formation of chalcopyrite ± electrum veins as Cu (–Au) mineralization at Heijianshan. This study suggests that the prolonged interaction contributes to sulfide formation and Cu (–Au) mineralization in these Paleozoic Fe–Cu or IOCG-like deposits formed in basin-related setting, and the Aqishan-Yamansu belt, Eastern Tianshan has gold mineralization potential.
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•Hamaling deposit is the first gold-copper-molybdenum deposit discovered in the Ordovician strata in the Tongling district, eastern China.•Hamaling deposit is developed porphyry-type ...ore in granodiorite, skarn-type ore at contact zone and breccias-type ore in Ordovician strata.•Hamaling deposit is associated with early Cretaceous magmatic activity in the Tongling district.•Hamaling deposit demonstrates a huge mineral exploration potential of the Lower Paleozoic strata in the Tongling district and even in the eastern China.
The Hamaling deposit represents the first discovery of a gold-copper-molybdenum deposit situated within the Ordovician strata of the Tongling ore-cluster region. It comprises three distinct types of ore, including porphyry-type Cu-Au ore found in granodiorite, skarn-type Cu-Au ore at the contact zone, and breccia-type Mo-Cu ore within the Ordovician strata. However, the exact mineralization age, ore genesis, and mineralization processes of the Hamaling deposit remain uncertain. To address these uncertainties, the present study employed LA-ICP-MS to date zircon in granodiorite and garnet in skarn, revealing ages of 139.3 ± 0.44 Ma and 142.3 ± 0.89 Ma, respectively. Additionally, the age of 140.0 ± 1.1 Ma was obtained through Re-Os dating of molybdenite from breccia-type ore. These findings suggest a connection between the Hamaling deposit and the early Cretaceous magmatic activity in the Tongling region. The granodiorite intrusion exhibits a high-potassium calc-alkaline affinity and formed under oxidized conditions at temperatures ranging from 721 to 832 °C (average 769 °C). The Hf isotope composition of the granodiorite implies its formation through the mixing of mantle-derived magma from an enriched lithospheric mantle with partially melted lower crustal source magma. The sulfur isotopes found in the ore minerals range from δ34S = 5.55 ‰ to 11.99 ‰, indicating a magmatic sulfur source. The H-O isotopic compositions of quartz during the quartz-sulfide stage suggest that the magmatic water was the primary component of the fluids responsible for ore formation, possibly with some contribution from meteoric water. The identification of the Hamaling deposit highlights the significant potential for mineral exploration within the Lower Paleozoic strata in the Tongling ore-cluster area and even the broader Middle-Lower Yangtze River Valley Metallogenic Belt (MLYB).
Multiple GH4169 samples were prepared with the regulation of the forming process of selective laser melting（SLM），particularly in laser power and scanning speed. The microstructure including defect ...morphology and distribution was observed by using metallography. The sample porosity was acquired using X-ray computed tomography（XCT），and the three-dimensional characteristics of defect were also statistically studied. The correlation of forming process and defect characteristics was finally analyzed. The results show that when the optimized energy input density is 59.1 J/mm3，the forming samples share common features of overlapping melting trace with a tidy morphology，randomly distributed pores with sizes of less than 30 μm and the density is as high as 99.9998%. Within a narrow window of forming process（220-300 W，700-1300 mm/s），the scanning speed takes more responsibility for the sample density，and its high value tends to form extremely irregular lack of fusions（LOFs） that distribute in the overlap of melting trac
To address the materials processing challenges resulting from high levels of heat input in wire arc additive manufacturing (WAAM), a novel wire arc metal additive manufacturing method using pulsed ...arc plasma (PAP-WAAM) was developed in this study. In this method, the pulsed arc plasma generated by the pulsed voltage was used as the heat source. Owing to the applied pulsed voltage, the arc plasma was alternately ignited and extinguished during additive manufacturing. By adjusting the relative positions of the tungsten electrode, filler wire, and substrate, the arc plasma was ignited between the tungsten electrode and the filler wire. This increased the proportion of discharge energy allocated to the filler wire, thus reducing the overall heat input required for material deposition. Furthermore, no heat was transferred to the deposited material because the arc plasma was extinguished during the discharge interval. Consequently, the previously deposited material was rapidly cooled. Preliminary experimental results showed that the newly developed PAP-WAAM process used 37 % less heat input than the conventional gas tungsten arc welding-based WAAM (GT-WAAM) process at the same wire feed speed of 350 mm/min. The PAP-WAAM process yielded smaller melt pools, higher cooling rates, and less heat accumulation than the GT-WAAM process, which was mainly attributed to the combined effects of low heat input and efficient heat dissipation by the pulsed discharge during PAP-WAAM. As a result, PAP-WAAM produced finer geometric features and microstructures as well as greater tensile strength than GT-WAAM.
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•A wire-based AM method using pulsed arc plasma generated by pulsed voltage as a fusion source was proposed.•The newly developed process used 37 % less heat input than the GT-WAAM process at the same wire feed speed of 350 mm/min.•The mechanisms for the reduced heat input required for material deposition during PAP-WAAM was investigated.•The influencing mechanisms of thermal behaviors on microstructural evolution and mechanical properties were investigated.
In the hot-rolling metal forming process, the consistency and accuracy of the thickness of the metal strip are the most important factors for the product quality control. The current method of ...utilizing a mechanism prediction model with pre-defined parameters does not perform well due to some limits on the model assumptions and environmental interference. Manually tuning these parameters of the mechanism model may even result in worse performance. To resolve this problem, an advanced randomized learner model, termed stochastic configuration network (SCN), is employed to build a data-driven prediction model which can be trained by using a dataset collected from a real-world hot-rolling production site. Based on the rolling theory and gray relational analysis (GRA), 36 features are selected as the inputs of the prediction model. Experimental results with comparisons show that our proposed method is feasible and outperforms other machine learning methods, such as deep learning models and the random vector functional link (RVFL) model.
The present study is conducted on forming of the metallic bipolar plates made of 316 stainless steel sheet with a parallel serpentine flow field. The plastic deformation of straight and curved ...microchannels, forming limit criteria, and deformation mechanics during the process are investigated partially to present a reliable model for estimating fracture initiation. For this purpose, experimental stamping tests are employed to fabricate metallic bipolar plates and the process is simulated by finite element software. The validity of simulation results is examined by comparing thickness distribution and force-displacement curves reflecting 4.76% and 3.85% error rates, respectively. According to experimental observations, fracture starts at a channel depth of 0.610 mm. Hence, for determining the forming limit and predicting the fracture during the process, the deformation mechanic is studied at different points of the microchannels. Results of stress states analysis indicate that the stress state of plane-strain tension up to biaxial tension governs this process. Despite the presence of different loading paths during the process, the critical element in each channel is deformed under plane-strain tension. Therefore, a fracture model is developed based on thinning percentage and equivalent strain to predict the instability of metallic bipolar plates. According to the results, both the equivalent strain and thinning percentage criteria with critical limits of 0.56 and 33.45%, respectively, are considered as an allowable range of plastic deformation during the conventional stamping process of bipolar plates. Results indicate that maximum thinning in all directions is lower than 33.45% by using the modified stamping process.
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•MBPP with higher depth/width is studied for raising power density and efficiency.•Detailed study of deformation mechanics of metallic bipolar plates is conducted.•An appropriate forming and fracture limit criteria is proposed.•Process is modified regarding thinning and equivalent plastic strain analysis.
As a crucial component of proton exchange membrane fuel cells (PEMFC), bipolar plates (BPPs) facilitate the transport of reactant gases, collection of current, and management of heat and water. This ...research provides a novel design and roll forming fabrication method for air-cooled metal BPPs. Furthermore, the application of carbon pre-coated 316L stainless steel can enhance manufacturing efficiency and reduce production costs. A 20-cell air-cooled PEMFC stack was fabricated with such metallic BPPs and its performance evaluations at different hydrogen inlet pressures were conducted. The testing results revealed that the stack could reach average output power of 299.4 W (power density 311.8 mW/cm2@0.535V) at a hydrogen inlet pressure of 0.06 MPa, during 50 h operation without significant degradation.
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•A novel design of metallic bipolar plates is provided.•The metallic bipolar plates are fabricated by roll forming process.•A 20-cell air-cooled PEMFC stack was assembled with the metallic bipolar plates.•The 20-cell stack operates for 50 h with an output power of around 300 W.
Skarn Cu deposits are one of most important deposit-type in Middle-Lower Yangtze River region, eastern China, but skarn formation process remains unclear. Mineralogical, morphological and in situ ...geochemical data from the skarn stage of Tongguanshan skarn Cu deposit in Tongling region are systemically investigated, to reveal the timing, physical-chemical conditions, and fluid evolution during the skarn formation. The Tongguanshan garnets can be identified homogeneous and unzoned early generation garnet (GrtI), and oscillating zoned late generation garnet (GrtII) with the Fe-rich core (GrtII-Fe) and Al-rich edge (GrtII-Al). Garnet U–Pb dating results show that the Tongguanshan Cu mineralization was formed in 145.6 ± 4.4 Ma. In situ elemental composition results of the garnet samples indicate that they belong to grossular-andradite solid solution series, and are a magmatic-hydrothermal origin. The distinctly geochemical characteristics (e.g., Sn and U contents, (La/Yb)N, δEu and Y/Ho values) reveal that the physiochemical conditions from GrtI to GrtII-Fe, and GrtII-Fe to GrtII-Al stages in the Tongguanshan skarn formation were an increase and a decrease of fluid salinity and oxygen fugacity, closed to open and then to closed of fluid environment, and neutral-weakly acidic to acidic and acidic to neutral-weakly acidic of fluid pH, respectively. A comprehensive discriminant analysis indicates a fluid boiling occurred in the GrtI to GrtII-Fe stage of the Tongguanshan skarn Cu deposit, and there is little or no external fluid mixed during the skarn stage.
