bluuebunny/crossref_metadata_2025 huggingface dataset:
Overcoming the Past to Create New Possibilities for Academic Achievement Among African American Males
Authors: Briggs Calvin , Bass Christopher K. , White Gerry
Published: May 2020

This chapter seeks to explore the need for the ongoing growth and development of collaborative efforts among institutions seeking to serve underserved and underprepared students, especially African American males, and their stakeholders. The chapter provides a brief historical context of public K-12 education and Historically Black Colleges and Universities. The objective is to provide context for today's academic challenges among African American males, subsequently providing alternatives to the current academic framework, revising the “pipeline” structure with an artery mode. This model reflects a holistic education framework that provides a strong cultural and social foundation; continuity in curriculum, education funding, and policy; and engages all constituents of the community, positively benefitting underserved families and students, particularly African American males.
Scouting as Community Support Opportunities for the Underserved to Exceed
Authors: Thomas Ursula
Published: May 2020

It is absolutely critical that we have grand conversations about supporting young males of color in our communities. Though this conversation is now front and center, it has not always been this way. There have always been some organizations that were having this conversation behind closed doors and quietly. Historic organizations like the Boy Scouts of America have acted as a conduit to allow communities of color to mentor and support their boys and young men in ways that were authentic to the needs of the community and the resources that the community had to offer. This case study examines that infrastructure and those resources through the eyes of an executive leader within Boy Scouts of America who is also an African American male. This is a case study of nonprofit accountability within communities of color.
Strategic Partnership for Family Leadership
Authors: Montemayor Aurelio M. , Chavkin Nancy Feyl
Published: May 2020

This chapter shares the organization background, theoretical frameworks, the case example of an Education CAFE model, challenges, and recommendations by the Intercultural Development Research Association (IDRA) from its more than 45 years of ground-breaking work in strategic partnerships focused on family leadership in education. The IDRA Education CAFE (Community Action Forums for Excellence) is a parent group that is rooted in a community-based organization, rather than in a single school. Its sole purpose is to collaborate with schools to improve the success of students in the community. IDRA developed the model through strategic partnerships with schools, families, and communities. It is the central focus of this case study illustrating lessons learned and next steps for successful strategic partnerships for family leadership in education.
Sports and Mentoring
Authors: Thomas Ursula
Published: May 2020

The involvement of young African American males in community and school-based athletics has been an ongoing conversation not only within the African American community but in the sports community at large. Often when we hear of African American males within athletics; be it collegiate or professional, it is often couched or enveloped in a negative connotation of some sort. But the primary impetus for this case study is to look at the importance of mentoring for African American male youth within community and school-based sports and how this is seen as a lifeline for community service and life lessons. This case study examines one leader's strategic approach to closing the achievement gap and providing mentoring with African American males through the sports-leadership nonprofit organization he manages.
Advocacy From the Ground Up
Authors: Smith Andrea N.
Published: May 2020

The history of education in the United States abounds with double themes and purposes for education: schooling for democratic citizenship and schooling for second-class citizenship. Although African Americans encountered significant legal barriers and threats of death while trying to obtain an education, their yearning for knowledge and opportunities served as a catalyst for education advocacy in their communities. In spite of various obstacles, researchers posit that African Americans erupted from slavery with a philosophy of education and perseverance that served as a precursor to the establishment of advocacy in education that would serve their needs and provide hope for a better education system. As a result, African Americans erupted from slavery with a philosophy of education and perseverance that served as a precursor to the establishment of universal schooling that would serve their needs and provide hope for a better life.
Research on the Operation Efficiency of Science and Technology Innovation Incubator Under Different Leading Modes
Authors: Zhang Meng , Pan Liyao , Du Xiaomin
Published: May 2020

The incubator of scientific and technological innovation plays an important role in leading scientific and technological innovation, accelerating the transformation of scientific and technological achievements, and promoting industrial upgrading and transformation. The Chinese economy is in the transition stage, so the research on the operating efficiency of the incubator of scientific and technological innovation based on the Chinese context has its unique value. In this study, combined with Chinese context, the business incubator is divided into two main modes: government and private. By using DEA research method, this chapter analyzes a series of problems, such as the overall difference and difference grade of the operating efficiency of incubators among the four major economic zones of China, the comparison of the operating efficiency of different modes between Northeast and Western regions, and the gap between private-led incubators in eastern China and private-led incubators in Northeast and Western China.
Review of Classical Intention-Based Entrepreneurial Models and Construction of Framework From Combined Perspectives of Entrepreneurial Motivation
Authors: Hou Fei , Su Yu , Qi Mingde , Lu Peixuan
Published: May 2020

An extraordinary proliferation of entrepreneurship education programs has been underway in recent years. One of key purposes of entrepreneurship education is to foster entrepreneurial intention. So how to predict and interpret the process of entrepreneurial intention becomes a dominant topic in academia. Under related entrepreneurial and psychological theories, reasoning and reviewing related classical entrepreneurial intention models, this chapter analyzes the influencing factors and interacting effects and proposes a path-model of entrepreneurial intentions from combined perspectives of entrepreneurial motivation and cognition in order to reveal the underlying psychological mechanism of entrepreneurial intention. The chapter hopes to have added richness to ongoing further researches among academics and discussions among educators and policymakers regarding the importance of entrepreneurial intention in entrepreneurial education.
Synthesis of Stir-Cast AA7050/5%B4C Composite and Optimization of EDM Response Parameters Using Taguchi Analysis
Authors: Kumar Arvind , Kumar Abhishek , Rai Ram Naresh
Published: May 2020

Machining of Automobile and aerospace components are the prime concern for close tolerance and eastern mechanical design. AA7050 is the established aluminium alloy for automobile and aerospace components. AA7050/B4C composite enhances specific strength and wear property of the alloy. The present paper aims to develop AA7050/5%B4C Composite through flux assisted Stir casting method. Characterized its microstructure for proper distribution and incorporation of the particles. Furthermore, non-conventional machining done on the composite through CNC die-sinking EDM with process parameters Peak current (Ip), Pulse on time (Ton), and Pulse off time (Toff). The experiments are designed by Taguchi L9 orthogonal array to obtain the machining responses like Material removal rate (MRR), Surface roughness, (SR) and cutting speed (Cs). Further the responses are optimised using Taguchi analysis considering higher the better criterion for MRR and Cs and lower the better for SR. The optimal set of process parameters obtained for MRR is X3Y3Z2, for SR X3Y2Z3 and Cs X3Y3Z2. The confirmation tests conducted with optimal set of process parameters for each response. The error estimated between predicted and experimental at optimal sets is within the acceptable threshold.
Analysis of the Effects of Welding Conditions on the Formation of the Structure of Welded Joints of Low-Carbon Low-Alloy Steels
Authors: Laukhin Dmytro , Pozniakov Valerii , Beketov Oleksandr , Rott Nataliia , Shchudro Anatolii
Published: May 2020

To obtain reliable joints in the conditions of open construction is complicated or impossible to use stationary machines and apparatuses, so requirements to welding processes are of special interest. The most interest concerning the support of strength and reliability of welded joint is specific processes developed after the crystallization of weld at weld zone. The value of the zone of thermal influence depends on the welding conditions and properties of metal that is welded. That is why the research on the influence of welding conditions on the formation of the structure of welded zone and thermal influence zone is actual.
Development and Research of Models and Processes of Formation in Silicon Plates p-n Junctions and Hidden Layers under the Influence of Ultrasonic Vibrations and Mechanical Stresses
Authors: Semenov Andriy , Baraban Serhii , Baraban Mariia , Zhahlovska Olena , Tsyrulnyk Serhii , Rudyk Andrii
Published: May 2020

In this article, mathematical models and processes of introducing homogeneous ultrasonic oscillations and mechanical stresses into silicon wafers in the direction of their thickness are developed and investigated, and mathematical models of the movement of interstitial defects in silicon wafers created by the processes of ion-beam transients at the transitions of ion-beam transitions and hidden dielectric layers using the action of ultrasound oscillations and mechanical stresses, both in the process of implantation of impurities and before the annealing of plates upon activation of the impurities are developed and investigated.
Compressibility of Palm Kernel Oil-Based Polyurethane Foam Using Rowe Cell Apparatus for Ground Improvement
Authors: Salleh Mohd Azwan , Jais Ismacahyadi Bagus Mohamed , Che Lat Diana , Samat Nastasa
Published: May 2020

Ground improvement methods are carried out to enhance the soil properties in order to ensure the unsuitable site locations with poor soil conditions can be developed for future development. Injection of lightweight material namely polyurethane foam is found to be one of the alternative methods that provide cost-effective and reliable techniques for ground improvement. Petroleum-based polyurethane is widely used in geotechnical application but nowadays the cost is getting more expensive due to high depleting rate and high production cost. Instead of using petroleum-based PU, this study is focusing on performance of palm kernel oil-based PU as an alternative method for ground improvement. The palm kernel oil-based polyurethane foam is anticipated to be more economical since it is produced from the renewable source, where it does not lead to permanent depletion of resources which has a limited global availability. The objective of this study is to determine the expansion and compressibility of palm kernel oil-based polyurethane with different mixing ratio. The samples were tested using Rowe cell apparatus to determine the compressibility, swelling index and pre-consolidation pressure of the polyurethane. The results of the finding show that the expansion and compressibility of the palm kernel oil-based polyurethane foam varies with the mixing ratio of isocyanate and polyol liquid. The compressibility index of PKO-BPU is found to be higher than petroleum-based polyurethane and low in expansion.
Thermodynamic Characteristics of Y2O3 and Y2S3 Nonmetallic Phase Formed in Liquid Steel
Authors: Gerasin Sergii , Kalisz Dorota , Iwanciw Jerzy
Published: May 2020

The current work deals the phenomenon of non-metallic inclusions as a result of the addition of Yttrium as an alloying component. The order of introducing individual components determines its final content in steel. This problem was analyzed using the WYK_Stal program developed at AGH-UST. Individual cases were considered using the accepted thermodynamics models based on Wagner’s formalism. The study of Y2O3 and Y2S3 phase precipitation and the relationship between the addition of Y, Al, Ca, O and S in molten steel was studied using the thermodynamic models. Based on the simulation, the authors stated that, the introduction of aluminum as the final deoxidizer into the liquid steel before the yttrium, results in the formation of non-metallic oxide inclusions. The low oxygen content in the metal bath promotes the formation of yttrium sulphide. In the case of calcium dosing, it is reasonable that, the yttrium is introduced after this element, which limits the losses on the formation of the yttrium sulphide phase.
Kinetic and Strength Calculation of Age-Hardening Phases in Heat-Resistant Aluminum Alloys with Silver
Authors: Wang Jin San
Published: May 2020

In order to study the microstructures of heat-resistant aluminium alloys with silver in process of aging, kinetic and strength calculation were used to study the equilibrium and metastable phases of Al-4Cu-0.3Mg-0.4Ag alloy system. The main equilibrium phases were Liquid phase, α-Al matrix phase, Al2Cu phase, S phase (Al2CuMg) and AgMg phase, while metastable strengthening phases were Ω phase and θ’ phase. In addition, the kinetic parameters and aging strength of_Ω phase and θ’ phase that precipitated during aging were calculated. The calculated results shows that Ω phase has higher heat-resistant strengthening effect than θ’ phase.
Effect of Graphene Content on Composition and Corrosion Resistance of Co-Ni-Graphene Composite Coating
Authors: Wei Guang Ning , Gao Er Long , Li Xue Song
Published: May 2020

The nanocrystalline CO-Ni-graphene composite coating were successfully fabricated onto the mild steel substrate by electrochemical co-deposition technique. The coating was prepared by changing the amount of added graphene at the bath temperature of 50°C, PH value of 4 and current density of 2A/dm2. Scanning electron microscopy (SEM), Energy dispersive spectroscopy (EDS) and X-ray diffractometer (XRD) were used to analyze the surface morphology, composition and phase structure of the coating. The prepared composite coating was then subjected to an impedance map in a 3.5% NaCl solution by a VersaSTAT3 electrochemical analyzer. The results show that the surface morphology of the coating was coarsened with the increase of graphene content in the electrolyte. The corrosion rate of the coating in the 3.5% NaCl solution first decreased and then increased, and the corrosion rate was 0.1998mA/cm2 at a content of 1.0 g/L.
Corrosion Behavior for Casing in Producing Well with Water Injection Technology during Long-Term Service
Authors: Sun Xin , Nan Rong Li , Shu Bo Zhao , Wang Hang , Zhu Li Juan , Han Li Hong
Published: May 2020

Corrosion leakage became serious due to cyclic sewage injection and continuous increase in water injection pressure. Corrosion behavior for N80 casing was studied during long-term service, using corrosion reaction kettle and weight loss method. The morphology and composition were characterized with laser confocal microscopy (LCM), scan electron microscopy (SEM) and energy disperse spectroscopy (EDS). These results showed that corrosion rate remained constantly at initial stage, and increased gradually, then sharply reached to 0.327mm/a at later stage, accompanying with inflection point under oxygen condition. Meanwhile, corrosion rate decreased significantly from 0.028mm/a to 0.020mm/a under oxygen-free condition. The corrosion of N80 steel was dominated by dissolved oxygen, and accelerated by chloridion. The micro-mechanism was suggested to be the transition of defect structure from crack with micron range to etch pit with millimeter range.
Effect of Strontium Modification on the Morphology of Primary Si in Hypereutectic Al-Si Alloys
Authors: Zhang Jing , Pang Zhou Yi , Sun Chi Chi , Liu Ning , Chen Hong Mei
Published: May 2020

In the present study, hypereutectic Al-Si alloys were modified by strontium and the effect of the strontium content and holding time on the morphology of primary Si was investigated. Primary Si is modified to imperfect octahedron with primary dendrites or secondary dendrites when the amount of Sr exceeds 0.04wt.%. With extending the holding time, there is no significant difference with the morphology of primary Si. However, the size of primary Si decreases remarkably when the holding time prolongs to 120min. Further analysis reveals that the Sr content has a considerable impact on the morphology of primary Si due to growth mechanism influence, while the modifying time mainly influences the size of primary Si.
Development Direction of Pipeline Corrosion Research on Oil Refining and Chemical Enterprises
Authors: Zhang Xiao Jia , Wang Rui , Yang Shang Yu
Published: May 2020

The corrosion behavior of refinery due to severe corrosive environment was investigated in the present study, and the analysis was focused on the guiding of the corrosion into a site where is near the ground, easy to change, have low risk and so on. The corrosion parts were analyzed to study the influences of the corrosion pipe in the whole systems. Some suggestions were proposed to choose the corrosion site that can happened. By using the developed method in this study the low risk position of pipeline as a sacrificial location can be found, and then taking it as the priority corrosion place under the control of switchable subline. It is therefore to shut down for maintenance of whole pipeline, and to easily replace the corrosion parts without stop all. The serious corrosion of refining pipeline system can consequently be reduced and removed, thereby to make the long-cycle operation of refining factory be realized.
Fracture Failure Analysis of C110 Oil Tube in a Western Oil Field
Authors: Zhu Li Xia , Kuang Xian Ren , Xiong Mao Xian , Xing Xing , Luo Jin Heng , Xie Jun Feng
Published: May 2020

There was an oil pipeline fracture found in the unlock process of Z well in western oilfield.The reason that made the oil tube fracturewassystematically studied usingmacroscopic analysis,physical and chemical property test,scanning electron microscope with an energy dispersive X-ray spectrometer and X-ray diffraction analysis.The results suggested that the requirement of relevant standard for C110 steel grade was satisfied with the chemical component and mechanical property of oil tube.The perforation of oil tube made H2S in the fluid medium enter the oil set of connected rings. In addition, the high-pressure gas left by gas contained certain H2S and O2 so that the tubewould fracture and be invalid under the combined action of sulfide stress corrosion and oxygen corrosion.
Experimental Study on Corrosion of Multi-Component Thermal Fluid Thermal Recovery well Tube String
Authors: Li Zhen , Zhao Pei Qi , Yang Cheng Hui , Liu Yin Lei , Ding Yin Chuan , Cui Lu
Published: May 2020

The thermal recovery well tube string is subjected to corrosion damage in multi-component gas aqueous solution during service period. Some severe damage such as thinning, perforation and even fracture of the pipe can have a serious impact on the stability and safety of the thermal recovery wells. In this paper, the high temperature and high pressure rotating sample reaction device is used to study the corrosion behavior of K55 casing steel and L80 tubing steel in high temperature environment of flowing multi-fluid. The results show the effects of O2 and CO2 concentration and temperature on pipe corrosion. Combining with the results of scanning electron microscope (SEM) and energy dispersive X-ray spectroscopy (EDS) analyses, we inferred the corrosion reaction process of tubes in different media and the corrosion behavior of two kinds of steel in the environment of multiple thermal fluids containing O2 and CO2 is clarified. Results show that the corrosion rates of K55 and L80 increase with the increase of O2 partial pressure and CO2 partial pressure, but the corrosion rates are positively correlated with temperature in oxygen-containing condition and negatively correlated with temperature in carbon dioxide-containing condition. The compactness of the corrosion product film has a large effect on the corrosion rate.
Microstructure and Macrosegregation of Ф508 mm 7050 Aluminum Alloy Billet under Internal Electromagnetic Stirring
Authors: Qiu Yang , Zhang Zhi Feng , Zhao Hao Dong , Xu Yong Tao
Published: May 2020

To obtain fine microstructure and homogeneous distribution of alloying elements in the large-sized billet, the internal electromagnetic stirring as a new electromagnetic stirring method was proposed and utilized for the preparation of Ф508 mm 7050 aluminum alloy billet. The results demonstrate that the internal electromagnetic stirring could refine the microstructure and second phase, and alleviated the macrosegregation significantly. The grain size at the edge, 1/2 radius, and center of the billet decreased to 180 μm, 175 μm, and 185 μm, respectively. Moreover, the relative macrosegregation of Zn, Mg, and Cu at the edge and center decreased to 3.9% and 2.8%, 2.3% and 1.6%, 4.1% and 2.5%, respectively.
Salt-Tolerance Performance of Oil Well Cement Fluid Loss Additive SSS/HAM/IA
Authors: Xiao Wei Yuan , Li Ming , Xie Dong Bo
Published: May 2020

In order to study the effect of brine environment on the performance of oil well cement fluid loss additive (FLA) sodium p-styrene sulfonate/N-methylol acrylamide/itaconic acid (SSS/HAM/IA), the water loss of three different cement slurry systems added with different FLA additions (fresh water cement slurry, semi-saturated brine cement slurry and saturated brine cement slurry) were tested at 90°C and 150°C. The results show that SSS/HAM/IA has good salt tolerance. The water loss of three cement slurry systems was controlled within 100mL with FLA addition adjusted in the range of 1%~3% below 150 °C. The salt tolerance mechanism of SSS/HAM/IA was analyzed based on the microstructure of the three system terpolymer solutions characterized under environmental scanning electron microscopy (ESEM).
Mechanical Properties and Microstructure of Slag Solidified Body
Authors: Yang Jun Lan , Li Ming , Liu Lu , Guo Xiao Yang
Published: May 2020

The mechanical properties of slag solidified bodies tend to be degraded when the temperature of slag solidified bodies is high. It is easy to crack under the action of perforated fracturing to lose the effect of sealing and interlayer sealing, and affect the cementing quality. Therefore, the mechanical properties of the solidified slag at several bottom-hole cyclic temperatures (30 °C, 50 °C, 70 °C, 90 °C) were studied in the present investigation. The results showed that the early strength of the slag solidified body cured at 90 °C was stronger than the early strength of the slag solidified body at 30 °C and 50 °C but lower than 70 °C. However, when the curing time reaches 28 days, the compressive strength of the slag solidified body at 90 °C droped sharply lower than the strength of the slag solidified body at 30°C. SEM and XRD indicated that the hydration products of slag at 90 °C were primarily network-like C-S-H gels. Compared with low temperature conditions, slag solidified bodies at high temperatures (>90 °C) were prone to micro-cracks and the structure easily damaged.
Effect of FCC Slurry on Performance of SBS Modified Bitumen
Authors: Zhang Tian Wei , Li Jian Xin , Mao San Peng , Zheng Gui Tao , Yu Jian Ying
Published: May 2020

Fluid catalytic cracking (FCC) slurry is a by-product of petrochemical industry rich in aromatics. In this paper, the effect of FCC slurry on the physical properties of SBS modified bitumen was investigated by softening point, penetration, ductility and low temperature flexibility test. The influence of FCC slurry on the compatibility of SBS modified bitumen was evaluated by fluorescence microscope and segregation test. The results show that FCC slurry improves the softening point, penetration, ductility and low temperature flexibility of SBS modified bitumen. Fluorescence microscope showed that FCC slurry promotes the dispersion of SBS in bitumen, which is conducive to the formation of network crosslinking structure of SBS modified bitumen. The segregation test indicated that the compatibility of SBS with bitumen was improved with the content of FCC slurry increasing.
Effect of Pore Structure and Ion Concentration of Solution on the Formation of Ettringite in Composite Cement Paste
Authors: Zheng Yan , Cui Su Ping
Published: May 2020

Under the background of shrinkage cracking of cement and concrete, ettringite is regarded as the most effective expansion source because of its outstanding expansion characteristics. In order to study the expansion mechanism of ettringite, the growth process and formation conditions of ettringite in composite cement system were studied by means of SEM, MIP and ICP. The effects of pore structure and ion concentration of pore solution on the morphology and expansion properties of ettringite were also analysed in this paper. The results show that the pore structure of cement paste directly affects the expansion properties of ettringite. It is verified that there is no obvious linear relationship between the expansion rate of ettringite and its quantity. The concentration of SO42- and Al(OH)4- in pore solution is the determinant of ettringite formation rate and quantity in composite cement system at the initial stage of hydration reaction. The change of crystallinity of ettringite will be directly caused by pH.
Determination of Antimony in Recycled Polyester Fiber by ICP-OES with Different Pretreatment Methods
Authors: Gao Ling Ling , Chen Ye , Wang Ning , Liu Shan Shan , Wang Yu Hui , Ke Fu You , Wang Chao Sheng , Wang Hua Ping
Published: May 2020

As consumer awareness of heavy metal content in textile increased, it is necessary to develop analytical methods that identify and quantify heavy metals. In order to comprehensively investigate the potential risks of antimony (Sb) in recycled polyester fiber to humans health, this study developed acid digestion method, with the condition that the volume ratio of concentrated sulfuric acid to hydrogen peroxide was 1, and digested at 200°Cfor 1.5h, which produced clear and colorless solutions.Currently, microwave and dry ashing are also common methods for digesting polyethylene terephthalate samples. Three pretreatment methods for determining the content of Sb in recycled polyester fibers was evaluated. Results showed that inductively coupled plasma-optical emission spectrometry (ICP-OES) analysis of acid digested recycled polyester samples resulted in Sb content higher than for the microwave and dry ashing digestion methods which incompletely digest recycled polyester. Moreover, compared with microwave digestion and dry ashing, acid digestion had a low detection limit of 0.0116 ug/mL, a high spike recovery of 82% to 106% and the RSD value less than 2%, which indicates that the data was accurate and reproducible. Therefore, in this study, acid digestion - ICP-OES was an effective method for detecting the content of heavy metal Sb in recycled polyester.
Effects of Process Parameters on Shrinkage Porosity in 357 Semi-Solid Die Casting Parts
Authors: Liu Zi Kang , Luo Min , Li Da Quan , Li Long Fei , Feng Jian
Published: May 2020

The shrinkage porosity that was caused by the insufficient feeding during solidification, was a common defect in the semi-solid die casting process. This defect decreased significantly the mechanical properties of the casting. In order to avoid the shrinkage porosity in casting, the die design, slug preparation and die casting process were carefully considered. In this study, a designed mold was used to make the sequential solidification of the slug. The process parameters, including intensification pressure, die temperature and biscuit thickness of the casting, were studied to show their influence on shrinkage porosity defects. The experimental results show that the high intensification pressure, high die temperature and long biscuit can be beneficial to obtain castings with no shrinkage porosity.
Microstructure, Texture and Mechanical Properties of Mg-Gd-Y-Zn-Zr Alloy during Repetitive Upsetting-Extrusion after Heat Treatment
Authors: Meng Ying Ze , Yu Jian Min , Zhang Zhi Min , Wu Yao Jin , Shi Zheng
Published: May 2020

Severe plastic deformation can be produced by repetitive upsetting-extrusion process. Using the repetitive upsetting-extrusion (RUE) process at decreasing temperature, the Mg-12.0Gd-4.5Y-2.0Zn-0.4Zr (wt %) alloy was deformed by different RUE passes and then heat treated. The microstructure, texture and mechanical properties of the alloy were compared and analyzed. The results demonstrate that with the increase of deformation passes, the coarse grains of the alloy decreased, the dynamic recrystallization fraction increased, and the dynamic recrystallized grains phagocytized the original grains. This can promote the continuous refinement of the grains and the microstructure uniformity. The maximum texture intensity of the (0001) basal plane decreased significantly with the increase of processing passes and the dispersion degree of pole figure increased. The orientation of dynamic recrystallized grains was randomly distributed to weaken texture. Due to the refinement of microstructure and the weakening of texture, the tensile strength and yield strength of the alloy obviously increased at room temperature. The mechanical properties of the alloy reached the highest after 3 passes and heat treatment.
Effect of Heat Treatment Process on Microstructure of a New Metastable β Titanium Alloy
Authors: Wang Xin Nan , Xin Yun Peng , Li Ming Bing , Zhu Zhi Shou , Zhao Guo Qun
Published: May 2020

The effects of solution temperature and aging temperature on microstructure of a new metastable β titanium alloy were studied. With the decrease of solution temperature, β grain size gradually decreased. When the solution temperature dropped to 780°C, the average grain size was about 10 μm. As the aging temperature increased from 500 °C to 560 °C, the secondary α phase increased. The nucleation of the secondary α phase within the grain was uniform, and its relationship with the β matrix was satisfied with Burgers. With the extension of aging time, the amount of the secondary α phases increased obviously, and they had a staggered arrangement with each other, presenting the phenomenon of the tensile strength increasing continuously. The strength level reached to 1500 MPa after aging at 500 °C for 8 h.
Effect of Combined Electromagnetic Fields on Microstructure and Properties of Large-Sized Ingot of 2219 Aluminum Alloy
Authors: Zhao Hao Dong , Zhang Zhi Feng , Qiu Yang , Li Bao , Gao Ming Wei
Published: May 2020

Large-sized 2219 aluminum alloy ingot has wide application prospect in aerospace and military fields. Severe defects, such as coarse grain, the inhomogeneity of structure and macrosegregation occurred in large-sized aluminum ingot produced by normal DC casting. The application of a single magnetic field in DC casting process cannot solve these defects. In this paper, a new method with the combination of electromagnetic fields imposed on bulk melt treatment during DC casting was proposed. And a φ508 mm ingot of 2219 aluminum alloy was prepared in this method. Compared with the normal DC casting, the effect of the combined electromagnetic fields on the microstructure and properties was studied. The experimental results demonstrate that the application of the combined electromagnetic fields significantly refines the grains, and the grain size distribution on the cross section of the ingot tends to be more uniform as well as the mechanical properties are significantly improved. The microstructure and grain size distribution can be significantly affected by different combined electromagnetic fields. It is considered that the appropriate combined electromagnetic fields parameters play an important role in controlling the homogeneity of large-sized ingots.
Mechanical Behavior and Microstructure of Hot Deformation of with Er 7N01 Aluminum Alloy
Authors: Zhang Bo Hou , Li Bo Long , Qi Peng , Li Ning , Wang Tong Bo , Nie Zuo Ren
Published: May 2020

In this paper, an Al-Zn-Mg-Cu alloy with a small amount of Er and Zr added was used as the research object. The homogenization annealing was carried out, and the 7N01 aluminum alloy was used at 300 °C, 350 °C, 400 °C, 450 °C and 0.1 s-1, 1 s-1, 10 s-1 deformation conditions by Gleeble-3500 thermal simulator. Optical Microscopy (OM), Scanning Electron Microscopy (SEM), Electron Backscatter Diffraction (EBSD) and Transmission Electron Microscopy (TEM) were used for microstructure analysis. The results show that the stress-strain curve of with Er 7N01 aluminum alloy can be divided into micro-strain stage, uniform deformation stage and steady-state flow stage during the thermal compression process. The flow stress of 7N01 aluminum alloy achieved peaks at the initial stage of strain, and then increased with the increase of strain rate and the decrease of deformation temperature. With the increase of deformation temperature and the decrease of deformation rate, the recrystallization process was significantly increased.
Effect of Solution Treatment on Second Phase Dissolution for an Al-9.2Zn-2.0Mg-1.9Cu Alloy
Authors: Liu Hong Wei , Wen Kai , Li Xi Wu , Li Zhi Hui , Yan Li Zhen , Yan Hong Wei , Zhang Yong An , Xiong Bai Qing
Published: May 2020

The second phase dissolution of Al-9.2Zn-2.0Mg-1.9Cu alloy conducted by various temperatures of 2h was researched with the help of optical microscope (OM), scanning electron microscope (SEM), energy dispersive spectroscopy (EDS), electrical conductivity and differential scanning calorimetry (DSC) analysis. The results gave rise to the second phase existence of Mg(Zn,Cu,Al)2 and Fe-containing phases in the as-extruded alloy. When the alloy solution treated with a temperature varied from 450°C to 470°C, a small quantity of Mg(Zn,Cu,Al)2 phase still existed in the alloy while its content exhibited a decrement trend with the solution temperature rose. For the alloy solution treated at a temperature of 475°C, Mg(Zn,Cu,Al)2 phase dissolved into the matrix completely while Fe-containing phase still remained. The electrical conductivity of quenched alloy decrease with the solution temperature increase and reached a minimum value at 470°C, and then rose slightly for the solution temperature of 475°C.
Analysis of Porosities in Nickel-Based Superalloys Powders
Authors: Yang Le Biao , Ren Xiao Na , Xia Min , Ge Chang Chun
Published: May 2020

In this paper, we investigated the porosities and their formation mechanism in the nickel-base superalloy powders, which were prepared by electrode induction melting argon atomization and divided into four particle size ranges: d＜60μm, 60μm≤d＜120μm,120μm≤d＜180μm, and d≥180μm. Firstly, the distribution of porosities in the powder were observed by Zeiss electron microscope. Secondly, the number and size of porosities in different particle size range were counted. Finally, the formation mechanism of the porosity was analyzed in details. The results show that the porosities are mainly distributed at the edge and center of the powders, and the size increases with the increase of the powder size. the porosity varies from a few microns to dozens of microns. the biggest pore size in the powder is approximately 120μm.There are no obviously porosities found in powders when their diameters are less than 60μm. While the porosity appeared as the powder diameter is more than 60μm. In addition, the proportion of the powder with porosities also increases with increasing powder size. When powders size is more than 180μm, the proportion of the powder with porosities reached about 91%. In general, the formation of porosities in powders are mainly ascribed to two reasons. the first one is a portion of argon was enclosed by the metal films during the spheroidization; the second one is the metal droplets uneven shrinkage during the solidification.
Development of Copper Alloy-Steel Bimetallic Bearing Materials and Manufacturing Technology
Authors: Wang Qi , Zheng Qi Fei , Li De Fu
Published: May 2020

Combining copper alloy with steel back to make bearing bush can not only improve the strength of bearing bush, but also prolong the life of bearing bush, which is called bimetallic bearing. In this paper, the development status of copper alloy materials in bimetallic bearing bushes and the manufacturing principle and characteristics of copper alloy-steel bimetallic bearing bushes are summarized, and the defects of several manufacturing processes are analyzed. This paper summarizes the research on improving the performance of copper-steel bimetallic bearing bush. Finally, the development direction of the preparation process of copper alloy-steel bimetal is prospected.
Preparation and Properties of Spherical Mo Powders by Plasma Rotating Electrode Process for Additive Manufacturing
Authors: Qiu Sha , Chen Bin Ke , Xiang Chang Shu
Published: May 2020

Since molybdenum has very high melting point of 2620 °C, there are many difficulties in its forming and post-processing, especially for deep processing. Furthermore as molybdenum is expensive, the utilization rate is important for the molybdenum processing. Additive manufacturing can directly manufacture the parts without mold and increase the utilization rate, and brings an opportunities for the new direction of deep processing for molybdenum. Due to the high quality requirements of molybdenum powder in additive manufacturing technology, the high-quality spherical molybdenum powder was prepared by plasma rotating electrode process method in the present study. The morphology, particle size and particle size distribution, chemical and physical properties were investigated. The molybdenum powder prepared by plasma rotating electrode process method showed to have high purity, high sphericity, good fluidity and high bulk density, proper particle size distribution and low gap element within the powder. The microstructure of the powder was a mixed structure of dendrites and cell crystals formed by rapid solidification, and as the particle size of the powder gradually decreased, the microstructure of the powder surface was remarkably refined. Within a certain range, the molybdenum powder with a wide particle size distribution had better fluidity and higher bulk density. The high-quality spherical molybdenum powder was prepared by plasma rotating electrode process method, which can meet the requirements of additive manufacturing technology for powder material performance.
Effects of Electromagnetic Agitation on Crystal Growth during the Pure Aluminum Slow Cooling Process
Authors: Wang Xiang Jie , Yu Fang , Li Peng Wei , Sun Wei , Tan Hong Juan , Li Lei , Cui Jian Zhong
Published: May 2020

Refining grains are important to obtain sound cast billets suitable for further processing. The structure refinement of low frequency electromagnetic field (LFEF) during the aluminum alloy semi-continuous casting process has been confirmed by many researchers. In this work, effects of the electromagnetic agitation on the crystal growth were investigated during the pure aluminum slow cooling process. The results showed that the grain refinement effect by electromagnetic agitation mainly occurred at the first half period of crystal growth. With increasing of applying LFEF treated time, the fine grain occupied the whole section of ingot, and the ratio of fine grain zone to the whole section was proportional to the treated time.
Microstructure and Texture Evolution of 0.6 mm Ultra-Thin-Walled Tubes of Magnesium Alloys Fabricated by Multi-Pass Variable Wall Thickness Extrusion (VWTE)
Authors: Yan Zhao Ming , Lian Zhen Dong , Fang Min , Zhang Zhi Min , Zhu Jia Xuan , Zhang Guan Shi , Zhang Long
Published: May 2020

AZ80+0.4%Ce alloy ultra-thin-walled tube with a wall thickness of 0.6 mm was fabricated by multi-pass variable wall thickness extrusion (VWTE) at 693 K. Microsturcture and texture evolution were investigated. The results indicate that the average grain size decreases from ~47 μm of extruded alloy to ~8.9 μm after 5 passes VWTE. The total area reduction of Mg alloy tube is 91 %. Homogeneity of microstructure is improved obviously and the morphology of Mg17Al12 phases in coarse grains and fine DRXed grains exhibit lamellar and granular shapes, respectively. In addition to the microstructure evolution, the VWTEed tubes showed a strong texture of (0001) planes, and the intensity decreased with deformation increasing to 4 passes. After 5p-VWTE, a strong texture characterized by (0001) pole tilting 20 degrees rotated from extrusion direction (ED) towards normal direction (ND).
Correlation between Solidified Microstructure Evolution and Undercooling of Au-12 Wt.%Ge Eutectic Alloy
Authors: Zhu Zhen Yong , Xiong Kai , He Jun Jie , Zhang Shun Meng , Xu Si Yong , Mao Yong
Published: May 2020

Highly undercooled solidification experiments were carried out by melt purification combined with cyclic superheating method on Au-12 wt.%Ge eutectic alloy. The solidification structures of Au-12 wt.%Ge eutectic alloy under different undercoolings were also analyzed by using the scanning electron microscope (SEM). The experimental results revealed that the maximum undercooling could reach up to 102 K. The microstructure analysis showed that the coarse bulk eutectic existed in the solidification structure when the undercooling was less than 34 K. When the undercooling was larger than 34 K and less than 56 K, the solidification structure transformed into cellular eutectic. The coarse primary (α-Au) phase precipitated from the undercooled alloy melt when the undercooling was larger than 56 K. The volume fraction of the primary (α-Au) phase gradually increased with the increase of undercooling. In this paper, a method to regulate the solidification structure of Au-12 wt.%Ge eutectic alloy is proposed, which provides a new way to improve the solidification structure and has important guiding significance for the processing and forming process of Au-12 wt.%Ge eutectic alloy.
Mechanical Response and Performance Relationship of X70 Pipeline Steel with Weld Zone
Authors: Wu Gang , Zhang Peng , Luo Jin Heng , Li Li Feng , Xu Guang Da , Zhu Li Xia
Published: May 2020

With the development of the natural gas industry, high flux natural gas pipelines will cause local deformation because of pressurization, which has an important effect in the service safety of pipeline materials. In this paper, the X70 pipeline steel with weld zone was studied, and the tensile test was used to simulate the uniaxial tensile stress. The results showed that the strain was mainly concentrated in the weld zone, which can imply that the weld zone has high strain hardening ability. The heat-affected zone with poor internal structure was prone to breakage. The research results can provide theoretical basis and experimental basis for pipeline steel welding process design and safety evaluation under high flux conditions.
Preparation and Properties of Halogen-Free Flame Retardant Polyurethane for Superfine Fiber Leather
Authors: Ke Hui Min , Zhu Ri Peng , Ma Jing Hong , Gong Jing Hua
Published: May 2020

Polyurethane (PU) superfine fiber leathers have been widely used in people's life. However, the flammability brings potential risks to their application. Therefore, more and more attention has been paid to the flame retardant modification of PU leathers. In the 1980s, researchers found that some brominated flame retardants produced dioxins during combustion. In 2007, the EU began implementing the REACH regulation, which restricted the use of certain halogenated flame retardants, so a majority of studies focused on halogen-free flame retardant modification. In addition, the halogen-free flame retardant PU should own a better alkali resistance, because alkali treatment is needed in the forming process of the superfine fiber leather. In this paper, two different halogen-free flame retardants were blended with solvent-based PU. The flame retardant properties and alkali resistance of the flame retardant PU were studied by limiting oxygen index (LOI) test, vertical burning (UL-94) test, and thermogravimetry-infrared spectroscopy (TG-FTIR). It was found that BY-90 system flame retardant could be uniformly dispersed in the PU matrix. And when its additive volume was 27%, the LOI value of the flame retardant PU was 27.1%, the vertical burning test could reach V-0 level. Moreover, it also had good alkali resistance. The LOI value remained at 26.1% after the alkali treatment at 90 °C for 40 min in the 30g/L NaOH solution.
Effect of Carbon Nanotubes Sizing Agent on the Mechanical Properties of Carbon Fiber/PP Composite
Authors: Gu Nian Liang , Chu Cai Xia , Guo Jun Nan , Ge He Yi , Jin Chao Sheng
Published: May 2020

In this paper, the surface of carbon fiber (CF) was firstly modified by carbon nanotubes (CNTs) sizing agent, then the CF reinforced polypropylene (PP) composite was prepared by extrusion-injection process. The tensile and flexural properties of CF/PP were tested. CF-5CNTs/PP had the best mechanical properties. The microstructure of CF and CF/PP was characterized by SEM. The effect of the CNTs on the mechanical properties of CF/PP was discussed in detail.
Synthesis of Four-Armed Star-Shaped Poly(N,N- Diethylacrylamide) by Group Transfer Polymerization in the Presence of Hydrosilylane
Authors: Li Jian , Kakuchi Toyoji , Shen Xian De
Published: May 2020

The core-first synthesis of four-armed star-shaped poly(N,N-diethylacrylamide) with predicted molecular weights and narrow molecular weight distributions (Mw/Mn=1.17) was carried out by the Tris(pentafluorophenyl)borane (B(C6F5)3) -catalyzed group transfer polymerization (GTP) using ethyldimethylsilane (EtMe2SiH) as hydrosilylane. The optimal ratio of the precursor to the hydrosilylation agent was 1:4.2.
Effect of Copoly(Ester-Amide 6)(PET-PA6) on Compatibility of PET/PA6 Blended Fibers
Authors: Shi Yu Kun , Xu Jin Long , Wang Song Lin , Yang Sheng Lin , Jin Jun Hong , Li Guang
Published: May 2020

Significant improvement of compatibility in PET/PA6 blends is essential to obtain fibers having enough mechanical strength as well as the comprehensive performance. In this article, copoly (ester-amide 6) was used as compatibilizer to improve the compatibility of PET and PA6. Three copoly (ester-amide 6) s with 5, 10% content of PA6 were prepared by co-polymerization from PTA , EG, as well as PA6 or caprolactam (A6), i.e. polyamide was incorporated both in the form of polymer and monomer, respectively. The sequence length of PET in the copoly (ester-amide 6) s is 33.4, 16.5 and 38.4 for PET-PA6-5%, PET-PA6-10% and PET-A6-5%, respectively, calculated by 13C NMR. Then PET/PA6 blend fibers were fabricated by melting spinning of PET and PA6 with 20 %wt addition of PET-PA6-5%, PET-PA6-10% and PET-A6-5%, respectively, to explore the effect of copoly (ester-amide 6) s on compatibility of PET/PA6 blend fibers, where the mass ratio of PET and PA6 is 85/15. DSC results show that the crystallization peaks of PET and PA6 during cooling from the blend melt become adjacent each other with increasing addition of copoly (ester-amide 6) s, even forming fused crystallization of them. It was found from SEM that the size of PA6 phase decreased and the phase boundary became indistinct due to the presence of copoly (ester-amide 6) s. Further more, the glass transition temperatures (Tg) of PET and PA6 closed to each other based on DMA result. Among these three copoly (ester-amide 6) s, PET-A6-5% display the best effect on the compatibility of PET and PA6 blend fiber, suggesting copoly (ester-amide 6) s could play important role in raise the compatibility of PET and PA6 blend.