不同的螺杆对聚合物加工性能的影响

在薄膜的加工中，对材料的加工性能是有特殊要求的，本文介绍了三种不同构形的螺杆，并对它们的性能进行了比较对照。

煤质对Texaco(GE)气化装置运行的影响及其选择

文中介绍了水煤浆加压气化适宜的煤种和Texaco煤气化工艺对煤质的要求及其选择适应性,分析了煤质对Texaco煤气化装置运行的影响。

Distribution of mineral species in different coal seams of Talcher coalfield and its transformation behavior at varying temperatures

Mineral phase characterization and thorough understanding of its transformation behavior during combustion are imperative to know the potential utilization of coal in the thermal industries. The primary objective of this work is to analyze the quality of Indian Coals and obtain their mineral species-specific information at different depths. The samples were obtained from Talcher Coalfield, Odisha, India. Coal from four seam sections in the Talcher coalfield, India are mainly high ash coal （〉50 %） and volatile matter deceases along with the seam depth. XRD results show that the major mineral phases present in the coal are quartz and kaolinite. Siderite, illite, and anatase were found in minor quantities. It has been observed that the clay minerals （kaolinite, silimanite, illite） decompose at higher temperature and traces of dolomite, mullite, hematite etc. are formed during the process of combustion. Among the four seams （M2, M12, M24 and M43） studied, ash of M43 has high A1203%, TIO2% and K20% content and low SIO2%, CaO% and MgO% content. High acid- to-base ratios contributed to high ash fusion temperatures （IDT 〉 1500 ℃） and low slagging potential of the coals studied. Relatively low fouling index （〈0.3） was estimated for all the coal seams studied. Furthermore, thermodynamic modeling software, FactSage, have been used to envision the mineral phase transformations that take place between 800 and 1500℃ during coal combustion.

Tensile Properties of Mechanically-Defibrated Cellulose Nanofiber-Reinforced Polylactic Acid Matrix Composites Fabricated by Fused Deposition Modeling

Biodegradable polymers are highly attractive as potential alternatives to petroleum-based polymers in an attempt to achieve carbon neutrality whilst maintaining the mechanical properties of the structures.Among these polymers,polylactic acid(PLA)is particularly promising due to its good mechanical properties,biocompatibility and thermoplasticity.In this work,we aim to enhance the mechanical properties of PLA using mechanically-defibrated cellulose nanofibers(CNFs)that exhibit remarkable mechanical properties and biodegradability.We also employ fused deposition modeling(FDM),one of the three-dimensional printing methods for thermoplastic polymers,for the low-cost fabrication of the products.Mechanically-defibrated CNF-reinforced PLA matrix composites are fabricated by FDM.Their tensile properties are investigated in two printing directions(0°/90°and+45°/-45°).The discussion about the relationship between printing direction and tensile behavoir of mechanically-defibrated CNF-reinforced PLA matrix composite is the unique point of this study.We further discuss the microstructure and fracture surface of mechanically-defibrated CNF-reinforced PLA matrix composite by scanning electron microscope.

Selective laser melted near-beta titanium alloy Ti-5Al-5Mo-5V-1Cr-1Fe:Microstructure and mechanical properties

In this work,a near-beta Ti-5Al-5Mo-5V-1Cr-1Fe titanium alloy was fabricated by selective laser melting(SLM),and the microstructure evolution together with the mechanical properties was studied.The as-fabricated alloy showed columnarβgrains spreading over multiple layers and paralleling to the building direction.The distinct microstructure of as-fabricated alloy was composed of near-β(more than 98.1%)with a submicron cellular structure.Different SLM processing parameters such as hatch spacing could affect the microstructure of as-fabricated alloy,which could thus further significantly affect the mechanical properties of as-fabricated alloy.In addition,the as-fabricated alloy with the distinct microstructure exhibits yield strength of 818 MPa combined with elongation of more than 19%,which shows that SLM is a potential technology for manufacturing near-beta titanium components.

Effect of direct electric current on wetting behavior of molten Bi on Cu substrate

The effect of direct electric current on the wetting behavior of molten Bi on Cu substrate at 370℃ was investigated by the sessile drop method. The wettability of molten Bi on Cu without an applied current is poor and the spreading time required to form the steady-state contact angle （about 102°） is approximately 30 min. With the increase of the applied electric current, the spreading of molten Bi on Cu is accelerated significantly and the steady-state contact angle decreases considerably. The cross-section SEM micrographs of the solidified Bi droplet on Cu substrate show that the electric current has a marked effect on the convection of melt. Correspondingly, the application of an electric current obviously enhances the dissolution of Cu into Bi melt, which may change the wetting triple line configuration. The improvement of wettability induced by electric current is also related to the additional driving force for wetting provided by the electromagnetic pressure gradient force.

Effect of refractory agent on ash fusibility temperatures of briquettet

To solve the problem of the low ash fusion point of briquette, this paper reported that the ash fusibility temperatures can be elevated by changing ash ingredients through blending refractory agents in briquette ash, which will create favorable conditions for moving bed continuous gasification of briquette with oxygen-rich air. The effects of A1203, SiO2, kaolin, dry powder and bentonite on ash fusibility temperatures were studied, based upon the relationship between briquette ash components and ash fusibility. The results show that the increasing of ash fusibility temperatures by adding the same amount （11%, w） of refractory agents follows the sequence of SiO2, bentonite, dry powder, kaolin, A1203, with the softening temperatures being elevated by 37.2, 57.6, 60.4, 82.6 and 104.4℃. With the same ratio of SIO2/A1203 in briquette, adding the A1203 component is more effective than SiO2 for raising ash fusibility temperatures. In this paper, inexpensive kaolin and bentonite rich in A1203 are found to be better refractory agents, and the suitable adding quantities are 9% and 11%, respectively.

Enhanced dehydrogenation kinetic properties and hydrogen storage reversibility of LiBH_4 confined in activated charcoal

LiBH4 was confined into activated charcoal（AC） by melt infiltration method（MI）, and its effects on the hydrogen sorption properties were investigated. The N2 adsorption results reveal that melt infiltration method can effectively incorporated LiBH4 into AC. It can maintain the structural integrity of the scaffold and ensure the confinement effect. The nano-confined LiBH4/AC starts to release hydrogen at around 190 °C, which is 160 °C lower than that of pure LiBH4, and reaches a hydrogen desorption capacity of 13.6% at 400 °C. When rehydrogenated under the condition of 6 MPa H2 and 350 °C, it has a reversible hydrogen storage capacity of 6%, while pure LiBH4 shows almost no reversible hydrogen storage capacity under the same condition. Mass spectrometry analysis（MS） results suggest that no diborane or other impurity gases are released in the decomposition process. The apparent activation energy of dehydrogenation of LiBH4 after confinement into AC decreases from 156.0 to 121.1 k J/mol, which leads to the eminent enhancement of dehydrogenation kinetics of LiBH4.

Synthesis and Study of Heteronuclear Citrates

Terms of synthesis were determined for creation of new generation premixes and for their testing in experiments. Heteronuclear chelate citrates of general formula： M12MnL2.nH2O （where, M^I = Zn, Co, Fe, Mn, Cu; MH = Mn, Zn, Co, Cu; n = 0/4） were synthesized. Identity and composition of synthesized compounds were defined by microelemental analysis, determination of melting temperature and X-ray diffraction analysis. X-ray diffraction method was used also to define crystallinity of the compounds and their citric acid （H4L） component. X-ray amorphous and iso-structural orders were also revealed.

Microstructure characteristics and effect of grain orientation on magnetic properties of Fe_(63)Co_(32)Gd_5 alloy ribbons

By using the melt spinning techniques, the Fe63Co32Gd5 alloy ribbons with 15-50 m in thickness and 3-7 mm in width were prepared at the wheel speeds of 15, 20, 25 and 35 m/s. The rapid solidification microstructures were characterized by three layers, the middle layer of which reaches 80% thickness and forms the column grain of(Fe,Co) solid with Gd solution. Grain refinement takes place with the increase of the wheel speed. And after 0.5 h heat treatment at 823 K, the ribbon thickness becomes larger and the middle layer of column grain is very orderly perpendicular to the ribbon plane. The coercivity of quenched and annealed Fe63Co32Gd5 ribbons both have the inflection point at the wheel speed of 20 m/s, and the tendency is declining. The heat treatment processing makes the coercivity become lower by improving the order of(Fe,Co)17Gd2 compound. The saturation magnetization of quenched ribbons increases with the enhancement of wheel speed, whereas that of annealed ones decreases firstly and then increases. The minimum coercivity is 5.30×103 A/m and the maximum saturation magnetization is 163.62 A·m2/kg, which is obtained in the conditions of the wheel speed of 35 m/s and 0.5 h heat treatment at the temperature of 823 K.

Influence of Post-Treatment Process on Microstructure and Properties of Laser Additively Manufactured Nickel-Based Superalloy

Defects such as cracks and micropores exist in nickel-based superalloy during laser powder bed fusion(LPBF),hindering their application in various fields.Hot isostatic pressing(HIP)was combined with conventional heat treatment(HT)to obtain LPBF nickel-based superalloy parts with ideal properties and fewer defects.The results show that HIP process can improve the densification,while the conventional HT can eliminate the micro-defects to improve the mechanical properties.After HIP treatment,the defect volume fraction of LPBF specimens decreases.After HT,the defect content of HIP+HT specimens increases slightly.After post-treatment,the hardness shows a decreasing trend,and the tensile strength and post-break elongation of HIP+HT specimens increase to 1326 MPa and 21.3%,respectively,at room temperature.

Bionic mechanical design and 3D printing of novel porous Ti6Al4V implants for biomedical applications

In maxillofacial surgery, there is a significant need for the design and fabrication of porous scaffolds with customizable bionic structures and mechanical properties suitable for bone tissue engineering. In this paper, we characterize the porous Ti6Al4V implant, which is one of the most promising and attractive biomedical applications due to the similarity of its modulus to human bones. We describe the mechanical properties of this implant, which we suggest is capable of providing important biological functions for bone tissue regeneration. We characterize a novel bionic design and fabrication process for porous implants. A design concept of “reducing dimensions and designing layer by layer” was used to construct layered slice and rod-connected mesh structure (LSRCMS) implants. Porous LSRCMS implants with different parameters and porosities were fabricated by selective laser melting (SLM). Printed samples were evaluated by microstructure characterization, specific mechanical properties were analyzed by mechanical tests, and finite element analysis was used to digitally calculate the stress characteristics of the LSRCMS under loading forces. Our results show that the samples fabricated by SLM had good structure printing quality with reasonable pore sizes. The porosity, pore size, and strut thickness of manufactured samples ranged from (60.95± 0.27)% to (81.23±0.32)%,(480±28) to (685±31)μm, and (263±28) to (265±28)μm, respectively. The compression results show that the Young’s modulus and the yield strength ranged from (2.23±0.03) to (6.36±0.06) GPa and (21.36±0.42) to (122.85±3.85) MPa, respectively. We also show that the Young’s modulus and yield strength of the LSRCMS samples can be predicted by the Gibson-Ashby model. Further, we prove the structural stability of our novel design by finite element analysis. Our results illustrate that our novel SLM-fabricated porous Ti6Al4V scaffolds based on an LSRCMS are a promising material for bone implants, and are potentially applicable to the field of bone defect repair.

Mantle geochemistry: Insights from ocean island basalts

The geochemical study of the Earth's mantle provides important constraints on our understanding of the formation and evolution of Earth, its internal structure, and the mantle dynamics. The bulk Earth composition is inferred by comparing terrestrial mantle rocks with chondrites, which leads to the chondritic Earth model. That is, Earth has the same relative proportions of refractory elements as that in chondrites, but it is depleted in volatiles. Ocean island basalts(OIB) may be produced by mantle plumes with possible deep origins; consequently, they provide unique opportunity to study the deep Earth. Isotopic variations within OIB can be described using a limited number of mantle endmembers, such as EM1, EM2 and HIMU, and they have been used to decipher important mantle processes. Introduction of crustal material into the deep mantle via subduction and delamination is important in generating mantle heterogeneity; however, there is active debate on how they were sampled by mantle melting, i.e.,the role of olivine-poor lithologies in the OIB petrogenesis. The origin and location of high 3He/4He mantle remain controversial,ranging from unprocessed(or less processed) primitive material in the lower mantle to highly processed materials with shallow origins, including ancient melting residues, mafic cumulates under arcs, and recycled hydrous minerals. Possible core-mantle interaction was hypothesized to introduce distinctive geochemical signatures such as radiogenic 186 Os and Fe and Ni enrichment in the OIB. Small but important variations in some short-lived nuclides, including 142 Nd, 182 W and several Xe isotopes, have been reported in ancient and modern terrestrial rocks, implying that the Earth's mantle must have been differentiated within the first 100 Myr of its formation, and the mantle is not efficiently homogenized by mantle convection.

Forming quality,mechanical properties,and anti-inflammatory activity of additive manufactured Zn–Nd alloy

Zinc(Zn)has recently been recognized as a promising bone repair material due to its inherent biodegradability and favorable biocompatibility.In this work,rare earth neodymium(Nd)was introduced into a Zn-based alloy fabricated using a laser powder bed fusion(LPBF)process.Results showed that addition of Nd significantly improved the melt fluidity and reduced the evaporation of Zn,thereby achieving parts with a high densification rate of 98.71%.Significantly,the Nd alloying treatment effectively refined the grain size from 25.3 to 6.2μm.Nd Zn5 eutectics precipitated and contributed to a second-phase strengthening effect.As a result,the tensile strength increased to(119.3±5.1)MPa and the Vickers hardness to(76.2±4.1).Moreover,the Zn–Nd alloy exhibited good anti-inflammatory activity,as the Nd ions released during degradation had a strong affinity with cell membrane phospholipids and consequently inhibited the release of inflammatory cytokines.It also presented favorable cytocompatibility,showing great potential as a bone repair material.

Development of soft magnetic amorphous alloys with distinctly high Fe content

This paper reports on the preparation of Fe82.7-85.7Si2-4.9B9.2-11.2P1.5.2.7C0,8 soft magnetic amorphous alloys with a distinctly high Fe content of 93.5-95.5 wt.% by component design and composition adjustment. All alloys can be readily fabricated into completely amorphous ribbon samples with good surface quality by the single copper roller melt-spinning method. These alloys show good bending ductility and excellent magnetic properties after annealing, i.e., low coercivity （He） of 3.3-5.9 A/m, high permeability （μe） of 5000-10000 and high flux saturation density （Bs） of 1.63-1.66 T. The mechanism of the good glass forming ability （GFA）and soft-magnetic properties are explored. The amorphous alloys with the high Fe content comparable to that of the desired high Si alloy can be promising candidates for the potential application in electric devices.

Self-healing materials enable free-standing seamless large-scale 3D printing

Three-dimensional(3 D)printing has had a large impact on various fields,with fused deposition modeling(FDM)being the most versatile and cost-effective 3 D printing technology.However,FDM often requires sacrificial support structures,which significantly complicates the processing and increases the cost.Furthermore,poor layer-to-layer adhesion greatly affects the mechanical stability of 3D-printed objects.Here,we present a new Print-Healing strategy to address the aforementioned challenges.A polymer ink(Cu-DOU-CPU)with synergetic triple dynamic bonds was developed to have excellent printability and room-temperature self-healing ability.Objects with various shapes were printed using a simple compact 3D printer,and readily assembled into large sophisticated architectures via self-healing.Triple dynamic bonds induce strong binding between layers.Additionally,damaged printed objects can spontaneously heal,which significantly elongates their service life.This work paves a simple and powerful way to solve the key bottlenecks in FDM 3D printing,and will have diverse applications.

Effect of melting heat transfer on peristalsis in the presence of thermal radiation and Joule heating

Mathematical model is developed for peristaltic flow of viscous fluid through a compliant wall channel subject to melting heat transfer. Fluid is incompressible and magnetohy- drodynamic. Analysis has been performed in the presence of Joule heating and thermal radiation. Solutions for small wave number are obtained. Physical quantities of interest are examined for various parameters of interest.

A precise and accurate acupoint location obtained on the face using consistency matrix pointwise fusion method

OBJECTIVE: To develop a more precise and accurate method, and identified a procedure to measure whether an acupoint had been correctly located.METHODS: On the face, we used an acupoint location from different acupuncture experts and obtained the most precise and accurate values of acupoint location based on the consistency information fusion algorithm, through a virtual simulation of the facial orientation coordinate system.RESULTS: Because of inconsistencies in each acupuncture expert's original data, the system error could not be modified using the characteristics ofthe general weight calculation. First, we corrected each expert of acupoint location system error itself,to obtain a rational quantification for each expert of acupuncture and moxibustion acupoint location consistent support degree, to obtain pointwise variable precision fusion results, to put every expert's acupuncture acupoint location fusion error enhanced to pointwise variable precision. Then, we more effectively used the measured characteristics of different acupuncture expert's acupoint location, to improve the measurement information utilization efficiency and acupuncture acupoint location precision and accuracy.CONCLUSION: Based on using the consistency matrix pointwise fusion method on the acupuncture experts' acupoint location values, each expert's acupoint location information could be calculated, and the most precise and accurate values of each expert's acupoint location could be obtained.