bluuebunny/crossref_metadata_2025 huggingface dataset:
Empirical Evidence on Corporate Governance Impact on CSR Disclosure in Developing Economies
Authors: Ben Rejeb Wajdi
Published: August 2016

This chapter investigates the influence of the board composition and leadership on Corporate Social Responsibility (CSR) disclosure. The empirical study of 68 Tunisian listed companies and 100 Egyptian listed companies reveals that board independence, foreign directorship, female directorship and state directorship, influence positively CSR disclosure. However, these findings indicate that CEO duality has a negative impact on CSR disclosure. Overall, the findings are consistent with the agency theory as well as the stakeholders theory and suggest that CSR disclosure seems to result from the willingness to meet shareholders' expectations in terms of transparency and voluntary disclosure of non-financial information.
Socially Responsible Mining Corporations
Authors: Yap Nonita T. , Ground Kerry E.
Published: August 2016

Mining is impact intensive regardless of commodity and scale. A socially responsible mining company, at a minimum, does not knowingly irreparably harm the community's ability to sustain itself after the mine closes. This chapter examines the mining sector in the Philippines: the public concerns, CSR responses and the challenges mining companies face in the country. Information was gathered through a review of academic and grey literature, key informant interviews and content analysis of Sustainability / CSR Reports. Many of the companies invest in the community as well as minimise their environmental impacts. A few invest in the community but appear to ignore people's right to a healthy environment. The chapter argues that mining can become an instrument for inclusive growth in the Philippines only if there is social peace, and that a streamlined and transparent mining policy regime, equitable benefits sharing and demilitarisation of mining areas will help bring this about.
CSR in China
Authors: Wolf Ruth , Thiel Monica
Published: August 2016

This chapter presents challenges in China's governance outlook within a Corporate Social Responsibility (CSR) analysis of China's social, environmental and economic resources and potential impacts in other countries. The purpose of this article sheds light of how CSR in China is emerging as a doorway to a) promote understanding of changes in firm governance for general managers through state and corporate socially responsible practices and b) to explain that preserving the environment and preventing pollution is necessary if China would like to trade with the West and enter global markets with other countries that place importance of governance and CSR principles.
The Call for Global Responsible Inter-Generational Leadership
Authors: Puaschunder Julia
Published: August 2016

Global systemic risks of climate change, over-indebtedness in the aftermath of the 2008/09 World Financial Crisis and the need for pension reform in the wake of an aging Western world population, currently raise attention for inter-generational fairness. Pressing social dilemmas beyond the control of singular nation states call for corporate social activities to back governmental regulation in crisis mitigation. The following chapter therefore promotes the idea of inter-generational equity in the corporate world to find an inclusive solution comprised by the public and private sectors. In the given literature on global responsible leadership in the corporate sector and contemporary Corporate Social Responsibility (CSR) models, inter-generational equity appears to have been neglected. While the notion of sustainability has been integrated in CSR models, inter-generational equity has hardly been touched on as for being a more legal case for codifying the triple bottom line. Advocating for integrating inter-generational equity concerns in CSR models in academia and practice holds untapped advantages of economically influential corporate entities, corporate adaptability and independence from voting cycles. Integrating a temporal dimension in contemporary CSR helps imbuing a longer-term perspective into the corporate world alongside advancing tax ethics and global governance crises prevention. Practical implications for the financing of an inter-generational harmonious solution on climate change burden sharing are proposed. Future research avenues comprise of investigating situational factors influencing inter-generational leadership in the international arena in order to advance the idea of corporations tackling the most pressing contemporary challenges of mankind.
Microstructural Dependence of Magnetization and Magnetostriction in Fe-20at.%Ga
Authors: Shi Yue Ming
Published: August 2016

A combination study of magnetic and magnetostrictive properties in directionally cast and differently heat-treated Fe-20Ga(at.%) samples has been carried out at room temperature. Slow cooling leads to an increase in the occupation of [200] easy magnetic axes; however, a structural ordering of Ga atoms into a metastable D03 phase decreasesthe saturation magnetostriction (λs) and the saturation magnetization (Ms), and increases coercivity (Hc).Our results confirm the contribution of D03 ordering to magnetic and magnetostrictive properties due to their pinning effects against magnetic domain wall motions. As compared to slow cooling, water quenching suppresses the formation of metastable (D03) or stable (L12) ordered phases and preserves the A2 single phase structure down to room temperature, leading to enhanced magnetostriction and magnetization.
Study on the Microstructure and Properties of Iron-Based Wear-Resistant Coating on the Inner Wall of an Aluminium Cylinder Block
Authors: Li Zeng Rong , Li De Yuan , Huang He , Wu Bi
Published: August 2016

An arc spray gun with inner holes was used to spray two typical iron-based wear-resistant coatings, 08A and 08CrMoVA, on the inner wall of an aluminum cylinder block for an engine. In addition, microstructures of the coatings were observed through an optical microscope and a scanning electron microscope. Then, X-ray diffraction (XRD) patterns were employed to analyze the types of oxides in the coatings, and a quantitative metallographic analyzer was applied to test the porosity and the amount of oxides in the coatings. Afterwards, the coatings were immersed in the oil to conduct the wearing test and the test result showed that the coatings had better wear resistance, compared with the gray cast iron. Besides, it was further found that the coatings were formed on the substrate surface by the accumulation of flat particles, and unmelted particles, oxides, pores and fissures were also found in the coating layer. While being lubricated by oil, FeO in the coatings and the oil stored in pores decreased the friction coefficient and thus increased the wear resistance of the coating layer.
Investigations on Interface Reactions and Wettability between Melt Superalloys and Ceramic Materials
Authors: Chen Xiao Yan , Li Fei , Wang Jun , Sun Bao De
Published: August 2016

Interface reactions and wettability between melt superalloys and ceramic mould materials were investigated by using a sessile drop experiment. The wetting angle of the melt alloy on the ceramic material was calculated and the microstructure of the alloy interface was investigated by metalloscope as well as SEM. It was found that active element C in the alloy is an important factor that influences the interface reactions and the wettability. Alloys with C content lower than 0.07wt.% were almost stable on the ceramic material and no interface reaction products were found. However, alloys with C content higher than 0.16wt.% reacted with the ceramic materials. Purple reaction products were found on the alloy surface and sand adhesions were observed at the alloy-ceramic interface. In the non-reactive system, the wetting angle is in the range of 135o-150o. In the reactive system, the wetting angle is lower than 120o.
Experimental Study of Failure Mode Transition in Semi-Crystalline Polymers Polypropylene under High Strain Rate
Authors: Liao Yu Gang , Zheng Hang , Tang Zhi Ping
Published: August 2016

The brittle to ductile failure mode transition and the formation of adiabatic shear bands (ASB) of polypropylene were observed at high strain rate impact loading. The dynamic experiments were conducted using a split Hopkinson pressure bar (SHPB) set-up with hat-shaped specimens. The post-test observations of the recovered specimens were performed by polarized light microscopy. The mechanical behaviors of specimens are strongly influenced by temperature, the strength of specimen decreases with increasing temperature. Furthermore, the specimen fractures as a brittle solid at room temperature (20°C), while at a high temperature (100°C), the specimen fractures on a ductile model. At high temperature impact tests, shear bands are observed in the shear zone of the hat-shaped specimen, and the cracks formed at the corners propagate along the shear bands.
Study on Ductile Brittle Transition Temperature of Q345C Steel MAG Welded Joints
Authors: Wu Yong Shou , Liu Yong Jun
Published: August 2016

For Q345C steel MAG welded joints, low temperature tensile test was carried out at normal atmospheric temperature, 0°C,-20°C,-30°C and-40°C in the paper, which results in the law of strength change with temperature. The impact absorption energy of the weld seam sample under different temperature conditions was tested, impact fracture morphology was observed and the parentage of the fibrous fracture surface was assessed. The curve of impact absorption energy and the percentage of the fibrous fracture surface with temperature were fitted by using the Boltzmann function, and ductile brittle transition temperature of Q345C steel MAG welded joints was determined. The test results show that the impact absorption energy of the weld seam can reach 71J at-40°C, and the weld seam is prone to brittle fracture under low temperature. The influences of alloying elements and microstructure on the ductile brittle transition temperature and low temperature impact toughness were discussed, and suggestion is put forward to improve the impact toughness and reduce the ductile brittle transition temperature.
Experimental Analyses about Ratcheting of Extruded 2017A Aluminum Alloy Subjected to Proportional and Non-Proportional Loadings
Authors: Brik Mouaad , Taleb Lakhdar
Published: August 2016

This work deals with the study of ratcheting for extruded 2017A aluminum alloy subjected to different loading conditions: unsymmetrical one-dimensional stress control as well as multi-dimensional combinations of stress-stress or stress-strain control. All tests have been conducted within the small strain assumption conditions at room temperature. The results point out the absence of ratcheting under unsymmetrical torsional stress control which enlarge the result given in (Taleb, L., 2013, Int. J. Plast., 43 (2013), 1-19) in which the absence of ratcheting under unsymmetrical tension-compression is demonstrated for the same material. However, under constant axial stress and cyclic shear strain, ratcheting is clearly observed. The results may be explained mainly by the evolution of the isotropic cyclic hardening exhibited by the material.
Influence of the Brittle Behavior of Work Materials on Microgrooving
Authors: Sakamoto Satoshi , Gemma Masaya , Hayashi Keitoku , Kondo Yasuo , Yamaguchi Kenji , Yamaguchi Mitsugu , Fujita Tsuyoshi
Published: August 2016

An electroplated diamond wire tool is frequently used for the machining of hard and brittle materials such as silicon ingots, magnetic materials, ceramics, and sapphires. This study aims to examine the influence of brittle behavior of work materials on machinability (including tool wear); therefore, we conduct dynamic ultramicro hardness measurements and microgrooving experiments for three types of ceramics. The results indicate that the groove depth of a work material tends to increase with the processing time. Moreover, material properties of a work material, such as hardness and toughness, have a significant impact on the fluctuations in its groove depth. However, kerf width of a work material does not depend on the processing conditions and material properties. In addition, a faster relative velocity improves processing efficiency but also increases tool wear.
Crack Observation of PPS Polymer Thrust Bearings under RCF Test in Water
Authors: Shi Xiao Chen , Ando Masatoshi , Kashima Yuji , Kida Katsuyuki
Published: August 2016

Polymer bearings are widely used under certain environments due to the advantages on light weight, low friction coefficient, high corrosion resistance and electric insulation. The main reason for polymer bearing failures in water was formation of flakings due to crack propagation. However, the mechanism of fatigue crack propagation in polymer material under rolling contact condition has not been clearly explained yet. In the present study, detailed crack observations were made on cross sections along both radial and rolling directions after RCF (Rolling Contact Fatigue) test in water using PPS thrust bearings.
Relationship between Failure and Temperature of PTFE Thrust Bearings under Dry Condition
Authors: Shi Xiao Chen , Kamiya Takayuki , Kashima Yuji , Kida Katsuyuki
Published: August 2016

Polymer bearings are attracting more and more attention due to the advantages on light weight, chemical and corrosion resistant, etc. PTFE owns the third-lowest friction coefficient within any known solid material, which makes it a considerable polymer material for bearing producing. In the present study, RCF tests under dry condition were carried out, and the relationship between failure and temperature of PTFE thrust bearings was investigated.
Backlash Evaluation of Hybrid UHMWPE-PEEK Bushes in a Small Robot Joint System
Authors: Kida Katsuyuki , Kawai Kota , Mizobe Koshiro , Koike Hitonobu , Kanemasu Kenji
Published: August 2016

In our previous work, we designed a new joint system for humanoid sized robot. This system consists of a servomotor, a harmonic drive and a link unit. This link unit includes three components; polymer bushes, a metal cam plate and a metal camshaft. However elastic deformation of all-polymer bushes can cause a large backlash in the system. In the present work, a new bush was developed and its fatigue behavior was investigated.
Effect of New Pocket Design on the Failure of Thrust UHMWPE Bearings in Dry Condition
Authors: Mizobe Koshiro , Fujimura Naoki , Kashima Yuji , Kida Katsuyuki
Published: August 2016

We developed a retainer with a new kind of design. This retainer has pockets with angles which we think could improve wear durability. We used ultra high molecular weight polyethylene (UHMWPE) because it is a tough thermoplastic polymer with self-lubrication ability. We performed rolling contact fatigue tests and found that wear durability was improved compared with the standard bearings.
Synthesis and Characterization of Poly(o-Methoxyaniline) Microsheets with pH-Sensitive Fluorescence Properties
Authors: Guo Yan Feng , Sun Dong Hao , Wang Ying
Published: August 2016

Functional poly(o-methoxyaniline) (POMA) microsheets are successfully synthesized in the presence of (NH4)3[CoMo6O24H6]·7H2O (CoMo6) under acidic conditions. It is proposed that the light-green CoMo6 precipitates formed in the initial reaction systerm serve as a polymerization reaction template for the formation of POMA microsheets. Moreover, POMA microsheets show pH-dependent fluorescence and exhibit enhanced fluorescence properties in comparision with POMA synthesized by conventional method in the absence of CoMo6.
Surface Modification of Nano-Al2O3 with Stearic Acid
Authors: Xu Min Hong , Ma Jian Li , Qian Meng Xia , Jiang Li Hua
Published: August 2016

Surface modification of nanoAl2O3 with stearic acid by dry method was researched. The structures of nanoAl2O3 before and after modified were characterized by IR. The modification effect on nanoAl2O3 was measured with the activation index. In addition, the influence factors of modifier dosage, modification time and modification temperature were also discussed. The results showed that nanoAl2O3 had been successfully modified with stearic acid. The hydrophily and lipophilicity experiments indicated that modified nanoAl2O3 possessed lipophilicity property and could disperse in xylene. The optimal conditions of modification were as follows: the stearic acid was 7.5 wt%, based on the quality of nanoAl2O3, modification time was 50 min and temperature was 150 ○C.
Study on the Synthesis of Waterborne UV Curable Polyurethane Acrylate
Authors: Liu Zhen Wen , He Jian Yun , Kang Wei Jia , Luo Xi Dan , Ding Yu Mei , Xie Peng Cheng
Published: August 2016

Water-brone UV-curable polyurethane acrylate was synthesized based on the toluene diisocynate, polypropylene glycol, dihydroxy methyl acrylic acid and hydroxyethyl acrylate. The structure and the influencing factors on the water solubility and photosensitivity of the waterbrone UV-curable polyurethane acrylate were analyzed. Results show that the water solubility of the resin is enhanced with the increasing of the content of hydrophilic group in the resin. The UV-curing rate of the waterborne coating is good by adding the 819-DW photoinitiator. Triethylamine is a good neutralizer in the waterbrone UV-curable system for having 90% neutralization degree.
Preparation and Characteristics of Highly Expandable Graphite Intercalation Compounds by Two-Step Chemical Intercalation
Authors: Li Xiao Xia , Zhao Ji Jin , Ma De Yue
Published: August 2016

Graphite intercalation compounds (GIC) are the most common precursors for expanded graphites which are promising materials for many applications. A series of GICs with different expanding volumes (EV) were prepared by a two-step chemical intercalation way. Effects of the input of oxidant and intercalating agent on the EV of GICs were discussed. The microstructures and morphologies of graphites before and after intercalation were analylized by X-ray diffraction and scanning electron microscope, respectively. The results show that the GIC with an EV of 600 ml⋅g-1 may be prepared under temperal conditions by a two-step intercalation way. The interlayer spacing of the pre-GIC formeded by one-step intercalation is a bit larger than that of natural graphites, while the interlayer spacing of the GIC obtained by two-step intercalation becomes much larger than that of the pre-GIC because of secondery intercalation. When the d-spacing (d002) value of the GIC rises from 0.3590 nm up to 0.3711nm, its EV increases from 267 up to 600 ml⋅g-1 due to the decomposition and release of much more intercalated substances during a thermal shock.
Research on the Preparation and Properties of UV-Curable Organic Silicon Nanomaterials
Authors: Luo Xi Dan , He Xue Tao , Xie Peng Cheng , He Jian Yun , Ding Yu Mei , Xia Bing Qian
Published: August 2016

New organic silicon nano-materials which has photo-curing performance was prepared by sol-gel method using γ-methacryloxy propylt rimethoxy silane as the starting materials. The micro-structures of the organic silicon nano-materials were characterized by FTIR and NMR. TEM was used to observe the nanometer particle size and the distribution of the nanometer particle in the organic silicon nanomaterials. The photo-curing properties of the new materials were tested. Results show that the new organic silicon nano-materials has uniform particle distribution and side chain of methacryloxy groups and can be UV-curing.
Characteristics and Biodegradation Properties of Poly(3-Hydroxybutyrate-co-3-Hydroxyvalerate)/Functionalized Graphene (PHBV/FGO) Blends
Authors: Hang Yi Ning , Wang Kun Yan , Li Bin
Published: August 2016

Poly(3-hydroxybutyrate-co-3-hydroxyvalerate)/functionalized graphene blends were prepared by solution blend method. The structure, thermal properties, thermal degradation and crystalline morphology were studied by X-ray diffraction (XRD), differential scanning calorimetry (DSC), thermogravimetry (TG), and polarizing optical microscopy (POM) analyses. Experimental results indicated that FGO increase the intensity of diffraction peak. Small-sized PHBV spherulites were formed. FGO affects the crystallization behavior of PHBV as heterogeneous nucleation agent. FGO acts as an effective thermal barrier due to its large aspect ratio and thereby hinders the degradtion of PHBV.
Preparation of Gypsum Retarding Material and Activated Carbon from Waste Mycelium
Authors: Chen Mi Mi , Zhang Meng Meng , Zhao Feng Qing
Published: August 2016

A clean and safe process of utilizing waste penicillin mycelium (WPM) was proposed in this paper. We treated WPM by soaking it in aqueous alkaline solution, to produce retarders for hemihydrate gypsum (the protein hydrolysate) by filtration. The filter cake was used to produce activated carbon, while the waste water can be reused for soaking process. This retarder can effectively prolong the setting time of gypsum with less drop in mechanical strength of gypsum plaster. The activated carbon produced with 674 mg/g of Iodine value, which meets the requirements of general industrial applications.
Photocatalytic Oxidative Decolorization of Methyl Orange with Iron Phthalocyanine/Calcium Alginate Gel Beads
Authors: Xu Min Hong , Ma Jian Li , Qian Meng Xia , Qin Hui Na
Published: August 2016

A photocatalyst iron phthalocyanine/calcium alginate gel bead (FePc@SA) was prepared through the mixture including iron tetra (N-carbonylacrylic) aminophthalocyanine (FePc) and sodium alginate dropped into 5 % (w/v) CaCl2 solution to get gel beads. The color of gel ball was black and the average diameters of gel ball before and after drying were 3.19 mm and 1.20 mm, respectively. Methyl orange was selected as a substrate to investigate the photocatalytic activity of FePc@SA. The results shown that the remaining rate of methyl orange was 19.51 % under the condition of methyl orange 10 mg/L 25 mL, pH value was 3, the dosage of H2O2 was 50 μL, FePc@SA was 0.2 g and visible light irradiation for 3 h. The results indicated that FePc@SA/H2O2 system had an obvious synergistic effect on photocatalytic oxidative decolorization of methyl orange. The decolorization process conformed to the first order kinetics equation, and the half-life of FePc@SA was 76.7 min. Simple preparation methods and excellent photocatalytic properties made FePc@SA became an ideal high performance photocatalytic material, which was applied to deal with wastewater containing organic pollutants.
Oxidative Decolorization of Azo Dyes with Copper Phthalocyanine Supported Mg-Al Hydrotalcites
Authors: Xu Min Hong , Ma Jian Li , Qian Meng Xia , Qin Hui Na
Published: August 2016

Oxidative decolorization of azo dyes with a heterogeneous catalyst copper phthalocyanine supported Mg-Al hydrotalcites was studied and the influence factors such as initial pH value, temperature, H2O2 and CuPc-LDHs/H2O2 system were discussed. The results indicated that acidic solution and high temperature were conducive to oxidative decoloration of methyl orange. CuPc-LDHs/H2O2 system showed excellent oxidative decoloration capacity to remove azo dyes. The effects of oxidative decolorization of azo dyes were related to the molecular structure and weight of azo dyes. Oxidative decoloration effects followed the order as congo red > amido black > methyl blue> methyl orange> methylene blue.
Simple Synthesis and Activities of Visible-Light Activities BiVO4 Doped Al via Solid State Method
Authors: Chen Hai Feng , Chen Jia Mei , Zhao Hui
Published: August 2016

Using the Bi (NO3)3•5H2O and NH4VO3 as raw materials, Al(NO3)3•9H2O provides Al3+ doping, BiVO4 photocatalysts with different Al3+ doping amount were successfully prepared by a low-temperature solid state grinding method. And it was characterized by XRD. The Methyl Orange (MO) was simulated as the degradation material under the visible light, which was used to study the influence of the amount of photocatalyst and the illumination time. The results showed that the catalytic effect of Al/BiVO4 photocatalysts was enhanced by comparing with pure BiVO4, but enhanced a little. And the possible causes of enhanced photocatalytic activity via doping have been discussed.
Facile Solid State Method Route Synthesis and Enhance Visible Light Activities of BiVO4 by Doping Co
Authors: Chen Hai Feng , Hu Jing Ling , Xu Bing
Published: August 2016

Using NH4VO3, Bi (NO3)3•5H2O and Co (NO3)2•6H2O as raw materials, Co doped BiVO4 (Co/BiVO4) photocatalysts were successfully prepared by solid state method. And the photo catalytic properties were test in this work. Crystal structures of these samples were characterized by X-ray diffraction (XRD). The Methyl Orange (MO) was simulated as the sewage under the visible light to explorer the influence of the illumination time and the mass of photocatalyst. The visible-light absorption spectrum of BiVO4 was broadening with doping Co. It was found that the Co/BiVO4 had higher photocatalytic activity than pure BiVO4 .The reason of enhanced catalytic effect also had been analyzed and discussed in the article.
Experimental Research on Adsorbents Preparation Made from Oily Sludge
Authors: Tang Chao , Guan Jiao Jiao
Published: August 2016

The objective of this study was to prepare adsorbents from two kinds of oily sludge and evaluate their adsorption characteristics. The results showed that the optimum conditions of adsorbent made from JL sludge was using ZnCl2 as activator, the concentration of activatorwas 0.5mol/L, solid-liquid ratio was 1:2, pyrolysis temperature was 550°C, staying time was 2h. The optimum conditions of adsorbent made from LH sludge was pyrolysis directly. Pyrolysis temperature was 650°C, staying time was 2h. The surface morphologies of two adsorbents were relatively rough and had irregular porous structure mainly in mesoporous. The iodine adsorption values of two adsorbents can reach 451.22mg/g and 376.48mg/g and the oil removal rate of simulated wastewater can reach 91.47% and 92.28% respectively.
3D Eddy Current Testing by FEM for Detection of Crack’s in Materials
Authors: Chabane Kahina , Harzallah Salaheddine , Chabaat Mohamed
Published: August 2016

In this paper, we present a nondestructive Testing by sensor Eddy current is used as a tool to control cracks and micro-cracks in materials. A new method for computing by measuring and testing related 3D Eddy currents is considered. In the process, a Potential Magnetic Vector is provided on the basis of formulations taken from the theoretical set up. Thus, results of relevant applications are obtained to check the theory consistency. A simulation by a numerical approach using Finite element discretization of 3-D Eddy Current governing equations is employed to detect cracks and damaged zones in materials and eventually to study their propagation.
Flexural Analysis for Tapered Cross-Section Steel-Concrete Material Composite Beam
Authors: Xia Jun , Shen Zhi Qiang , Liu Kun
Published: August 2016

The flexural behavior of tapered cross-section steel-concrete composite material beams frequently used in structural engineering is strongly influenced by the type of shear connection between the steel beam and the concrete slab. The 1D high order finite element model for tapered cross-section steel-concrete composite material beams with interlayer slip were established in this paper. The Numerical results for deflection and interlayer slip of the composite beam with two typical boundary conditions were compared with ANSYS using 2D plane stress element. The 1D element is more efficient and economical for the common tapered cross-section steel-concrete composite material beams in engineering.
Changes in Magnetic Flux Density Distributions of Chromium Molybdenum Steel (JIS, SCM440) by Slit Opening and Crack Growth
Authors: Kida Katsuyuki , Nakashima Tatsurou , Ishida Masayuki
Published: August 2016

Non-destructive evaluation methods using magnetic measurement systems have been developed. However, there are a few approaches to the effect of cracks on magnetic fields during whole fatigue process. In the present work, slit samples of as-received chromium molybdenum steel material (JIS, SCM440) including no retained austenite was fatigue tested. Fatigue process was observed using a scanning Hall probe microscope in order to investigate the effect of cyclic slit opening and crack growth on residual magnetic fields. It is found that the cyclic opening-closing of the slit decreases the magnetic flux density even where no tensile stress was applied.
Effect of Aluminum Insertion Material on the Properties of AAC
Authors: Pan Yun Feng , Huang Wan Ming , Jiang Ya Qing , Song Qiang
Published: August 2016

Study on the compressive strength, shrinkage and effect of aluminum insertion materials on the hydration products of Autoclaved Aerated Concrete (AAC). The types and properties of hydration products are studied by X-Ray Diffraction Analysis (XRD), Differential Thermal Analysis (DTA), Scanning Electron Microscope analysis (SEM) and so on. The results showed that the strength and the shrinkage resistance capability of the product could be improved effectively. Al3+successfully doped into C-S-H gel and tobermorite crystals, then replaced si4+of tobermorite and formed the system of C-A-S-H. Tobermorite in aluminum insertion aerated concrete is smaller and more compact. All hydration products interlace to form a whole, then the structure turns denser. Low porosity, high crystal gel volume ratio and high hydration degree are the key of the high strength aluminum insertion aerated concrete. Aluminum insertion materials improve the performance of the products.
Toughening Effects of Carbon Nanotubes on 3Y-ZrO2 via Different Material Molding Technologies
Authors: Wang Cui Can , Chen Chang Lian , Luo Ma Yo , Huang Xiao Yu , Huang Zhi Liang
Published: August 2016

In order to research the toughening effects of carbon nanotubes on 3Y-ZrO2 via different moulding methods. 3Y-ZrO2 and 3Y-ZrO2 with two kind of carbon nanotubes were prepared by compression moluding forming and gel-casting. And all of the green bodies were sintering at 1600°C in high temperature furnace. The X-ray diffraction and density of sintered bodies, microstructural of fracture surface and fracture toughness were characterized and analyzed. Results shown that gel-casting is better than compression about toughening 3Y-ZrO2 by carbon nanotubes. For gel-casting, the density is nearly the same and fracture toughness has been improved which is form 5.17MPa·m1/2 to 5.63 MPa·m1/2. For compression moulding forming, the density was reduced by the aggregation of carbon nanotubes. The fracture toughness can’t improve by carbon nanotubes.
Two-Component Metal Injection Moulding of Ti-6Al-4V and Stainless Steel Bi-Material Parts
Authors: Mulser Marco , Petzoldt Frank
Published: August 2016

Two-component metal injection moulding (2C-MIM) allows producing functionally graded metal parts of complex shape by co-sintering. Until now several studies have demonstrated that different material properties can be combined. Another promising material combination is titanium and iron-based materials. It can combine the biocompatibility and low density of titanium with a ductile and cost efficient stainless steel. However, co-sintering these materials reveals challenges due to a significant mismatch in sintering shrinkage and limitations in sintering temperature for both materials. The recent study showed that Ti-6Al-4V can be joined to the stainless steel 316L by 2C-MIM provided that certain constraints are taken in account. The quality of the interface before and after co-sintering is a crucial factor for intact parts after processing. By applying sinterdilatometry the mismatch in shrinkage was compensated by using adjusted powder characteristics and tailored feedstock compositions. A co-sintering cycle was defined with regard to the sintering characteristics of both materials. The developed two-component specimens revealed significant interdiffusion of alloying elements at the Ti-6Al-4V / 316L interface and a tensile strength of 282 MPa after co-sintering.
Metal Injection Moulding of Titanium Medical Components
Authors: Friederici Vera , Hartwig Thomas
Published: August 2016

The metal injection moulding technique is already established for serial production of complex parts, mostly from various stainless steels. However, for other materials, especially for titanium parts there is still the need for superior purity and enhanced surface quality. Facing the challenge of obtaining suitable medical titanium MIM parts, advances have been made at Fraunhofer IFAM over the last few years.One strategy to overcome the high risk of carbon up-take was to adjust the sintering program. Very low Argon flow rates, 50 mbar pressure and two hours dwell time at 1350°C were found to be optimal parameters. A cleaning cycle prior to the actual sintering at 1450°C under hydrogen was also found to enhance the results.Another strategy involved the choice of binder components. Stearic acid, which is often used to improve wettability of binder to powder particle, and high polymer content affect the oxygen content of the titanium parts. Low amounts of both are beneficial for high purity parts.Other investigations were performed concerning the surface quality. It was found that the surface roughness of the mould has an effect on the surface roughness of the sintered parts. Although sintered titanium surfaces as such exhibit quite rough surfaces of about 2-3 µm (Ra value) the influence of the surface finish of the mould was detectable. Using very fine powders of only 15 µm mean particle size and a polished mould a very low surface roughness of less than 1.2 µm on the sintered part was obtainable.
Microstructures and Mechanical Properties of Ti-43Al-5V-4Nb-Y Alloy Consolidated by Spark Plasma Sintering
Authors: Su Yong Jun , Zheng Yi Feng , Zhang De Liang , Kong Fan Tao
Published: August 2016

TiAl alloy with a composition of Ti-43Al-5V-4Nb-Y (at.%) was prepared by spark plasma sintering (SPS). The TiAl powders were sintered between 650°C and 1300°C for 5 min under different loads. With the increasing of the temperature, the diffusion of the elements can be observed. Full compaction is achieved in a short period of time and the overall processing duration does not exceed 30 min. A fully lamellar structure was seen in the TiAl alloy after heat treatment. The microstructures of the samples were determined by X-ray diffraction and scanning electron microscopy. Their mechanical properties were evaluated by tensile tests performed at room temperature
Creep Properties of Ti-48Al-2Cr-2Nb Produced by Selective Electron Beam Melting
Authors: Juechter Vera , Körner Carolin
Published: August 2016

Titanium aluminides are highly attractive for high temperature applications involving dynamic components, e.g. turbine blades or turbocharger wheels, due to their high strength-to-weight ratio. The drawback is the difficult manufacturing of this material class due to the low toughness and high sensitivity to oxygen. Selective electron beam melting SEBM shows a new approach of producing complex titanium aluminide parts without a major oxygen pick up and avoiding problems with brittleness. The high cooling rates of this process lead to a very fine microstructure, which is not fully understood up to now. The microstructure determines the creep properties and therefore defines the performance of this material in high temperature applications. In this contribution, the creep properties of Ti-48Al-2Cr-2Nb fabricated by SEBM are investigated. The influence of the processing parameters and the building direction on the microstructure and the creep properties are discussed and compared to cast material.
Processing and Characterization of Porous Ti2AlC Using Space Holder Technique
Authors: Gonzalez-Julian Jesus , Bram Martin
Published: August 2016

Ti2AlC is one of the most promising MAX phase materials due to its combination of properties at high temperatures (> 800 °C) such as high strength, good oxidation and corrosion resistances, low thermal expansion, readily machinable, high thermal conductivity and nonsusceptibility to thermal shock. Porous structures based on Ti2AlC are excellent candidates for diverse applications such as heat exchangers and filters, although more systematic studies are required to implement this material. In this work, porous Ti2AlC material was obtained using a low cost and eco-friendly process, the space holder technique. Commercial Ti2AlC powder was mixed with different contents (30, 50 and 70 vol.%) of ammonium hydrogen bicarbonate (NH4HCO3) as space holder. Afterwards, the obtained powder was uniaxially pressed, followed by elimination of space holder by a heat treatment at low temperature. Finally, porous Ti2AlC structures were consolidated at 1350 °C under argon atmosphere. Processing, final microstructure and pore characterization of the consolidated materials are described in detail.
Mechanical Properties of Ti-6Al-4V Fabricated by Electron Beam Melting
Authors: Kirchner Alexander , Klöden Burghardt , Weißgärber Thomas , Kieback Bernd , Schoberth Achim , Greitemeier Daniel , Bagehorn Sarah
Published: August 2016

Powder bed additive manufacturing of titanium components offers several advantages. The high freedom of design enables the fabrication of structurally optimized, lightweight parts. Complex geometries may serve additional functions. The use of additive manufacturing has the potential to revolutionize logistics by dramatically reducing lead time and enabling a high degree of customization. Manufacturing near net shape parts reduces the loss of expensive material.For the application in safety relevant parts certainty about static and fatigue strength is critical. A challenge arises from complex influences of built parameters, heat treatments and surface quality. Ti-6Al-4V specimen built by electron beam melting (EBM) were subjected to heat treatments adapted to various employment scenarios. The results of tensile and fatigue testing as well as crack propagation and fractography will be compared to titanium manufactured conventionally and by selective laser melting (SLM). The mechanical behavior will be correlated to the microstructural evolution caused by the heat treatments
Thermohydrogen Processing of 3D Screen Printed Titanium Parts
Authors: Jurisch Marie , Studnitzky Thomas , Andersen Olaf , Kieback Bernd
Published: August 2016

The present study addresses the need for grain refinement in free sintered titanium alloys produced by 3D screen printing. Thermohydrogen processing (THP) was used for temporary alloying Ti-6Al-4V with hydrogen to refine its microstructure. The impact on microstructure was investigated by a parameter study with varying temperatures, exposure times and hydrogen partial pressures. Heat treated specimens were examined by optical microscopy, XRD and thermal analysis. The influence of the refined microstructure on the mechanical properties was evaluated by tensile and microhardness testing. Ultrafine grained microstructures with ultimate tensile strengths of up to more than 1000 MPa could be produced.
Processing and Characterization of Ti-6Al-4V Samples Manufactured by Selective Laser Melting
Authors: Sarria Perla , Torres Yadir , Gotor Francisco José , Gutiérrez Eliel , Rodríguez Melchor , González Ramón , Hernández Laura , Peón Eduardo , Guerra Hugo , González Jesús E.
Published: August 2016

Titanium and its alloys are well known as one of the best in-vitro and in-vivo bone replacement metallic biomaterial due to its excellent balance between biomechanical and biofunctional properties. The selective laser melting (SLM) method has a lower cost and shorter manufacturing time than the conventional routes used in the fabrication of titanium alloys. In this work, Ti6Al4V sheets were manufactured by SLM (LM samples) and subsequently annealed for stress relief at 750 oC for 10 min (LM-A samples). SEM, XRD and contact profilometry measurements were carried out to characterize the elemental composition, phases and surface morphology of different samples. A micro-tribo-mechanical evaluation was also performed by micro-indentation and scratch tests. The resulting surface was rough (Ra = 9.1 ± 0.5 μm) for all samples, showing protuberances with spherical morphology. For annealed samples, an oxide layer composed of rutile and Al2O3 was observed that increased the micro-hardness of the surface in LM-A sheets. However, after removing this oxide layer, the micro-hardness of the LM-A sheets was reduced when compared to LM samples as a result of the stress relief. A direct relationship between Vickers micro-hardness and scratch resistance was always observed. Therefore, LM-A sheets showed higher scratch resistance at low loads (oxidized surface effect) than LM samples, but lower resistance at high loads (bulk effect).
Induction Plasma Technology Applied to Powder Manufacturing: Example of Titanium-Based Materials
Authors: Vert Romain , Pontone Remy , Dolbec Richard , Dionne Luc , Boulos M.I.
Published: August 2016

Powder metallurgy technologies require specific powders to ensure a good quality to the manufactured parts. The critical properties are; the powder chemistry, flow ability, packing density, and the absence of porosity. This review highlights the capability of Tekna’s Inductively Coupled Plasma (ICP) technology for the production of high quality powders for the additive manufacturing industry.
Powder Metallurgy Ti-6Al-4V Alloy with Wrought-Like Microstructure and Mechanical Properties by Hydrogen Sintering
Authors: Dunstan Matt , Fang Z. Zak , Koopman Mark , Paramore James
Published: August 2016

Hydrogen sintering phase transformation (HSPT) is a low-cost, blended elemental, press and sinter powder metallurgy process. During HSPT, compacts of TiH2 powder are sintered in dynamically controlled partial pressures of hydrogen followed by a vacuum anneal (dehydrogenation). The use of hydrogen in the sintering atmosphere allows phase transformations in the Ti – H system to create an ultra-fine lamellar microstructure in the as-sintered state with mechanical properties that exceed ASTM standards. Additionally, the fine lamellar structure allows for secondary heat treatments to produce wrought-like microstructures. The removal of hydrogen in the dehydrogenation step is critical to prevent hydrogen embrittlement. The kinetics of dehydrogenation are discussed, in which a model for the concentration profile and an empirical equation for maximum hydrogen concentration as a function of time and size are developed.
Characterization of Simultaneously Gas Atomized Ti/TiC Composite Powders
Authors: Yeh Tze Yang , Peng Kuo Yuan
Published: August 2016

Metallic composite materials are mainly manufactured by powder metallurgy (PM) or casting, with reinforced ceramic particulates dispersed in a metal matrix. The current study presents an investigation with respect to simultaneously gas-atomized spherical Ti/TiC composite powders. Various analytical methods are used to characterize the gas-atomized Ti/TiC composite powders, including XRD, laser particle size analysis, flow rate tests, apparent density and tap density tests, SEM, and alike. The spherical Ti/TiC composite powders will be further laser sintered at the next stage to utilize mechanical properties testing.
Development of Ti-22Nb-xZr Using Metal Injection Moulding for Biomedical Applications
Authors: Nagaram Anok Babu , Ebel Thomas
Published: August 2016

Research on biomaterials is connected inherently with the various aspects of materials science, chemistry, biology and medicine. Frequently used biomaterials for implants are titanium alloys because of their high corrosion resistance and biocompatible behaviour together with high strength and low density. One main characteristic property for the consideration of a potential implant material is the Young’s modulus which should correspond to that of human bone (4~30 GPa) as close as possible. β-Ti alloys exhibit currently the lowest value of typically 60 to 80GPa. β-Ti phase is stabilized with additive elements such as Mo, Ta, Hf and Nb. In particular, Ti-Nb alloys can exhibit a Young’s modulus around 50 to 60 GPa. Metal Injection Moulding (MIM) is a promising production technology because it overcomes the productivity and shape limitations of traditional powder compaction methods. However, formation of carbide precipitates at the grain boundaries deteriorating the ductile behavior of the materialhas become a challenge in MIM. Recent research using MIM on Ti-22Nb with the addition of Zr has revealed the reduction of carbide precipitates. In this study, different amounts of zirconium were added varying between 2 to 10 wt%. Samples produced with 10% Zr revealed the highest tensile strength of 840 MPa. In addition, specimens with higher zirconium content showed the highest ductility. XRD measurements revealed an increase in lattice constant effecting an increase of the carbon solubility of the Ti-matrix and, thus, a reduction of the carbide precipitation.
Electrophoretic Deposition of PEEK/45S5 Bioactive Glass Coating on Porous Titanium Substrate: Influence of Processing Conditions and Porosity Parameters
Authors: Torres Yadir , Romero Carlos , Chen Qiang , Pérez Gonzalo , Rodríguez-Ortiz José Antonio , Pavón Juan José , Álvarez Laura , Arévalo Cristina M. , Boccaccini Aldo Roberto
Published: August 2016

Commercially pure titanium (cp Ti) is typically accepted as one of the best in vitro and in vivo bone replacement biomaterial, due to its excellent balance between biomechanical and biofunctional properties. In that context, the aim of this work is to prove the hypothesis of a simultaneous solution to certain specific limitations of cpTi, which can often compromise the reliability of implants: (i) stress-shielding phenomenon, and (ii) a deficient biointerface with bone, which reduces the osseointegration. Porous samples of cp Ti, grade IV, were obtained by space-holder technique (50 vol.% NH4HCO3, 800 MPa, at 1250 oC during 2h, under high vacuum), to produce a good balance between Young ́s Modulus and yield strength. Different types of porous samples were manufactured by considering different size particles ranges of NH4HCO3: 100-200μm, 250-355μm and 355-500μm. Afterwards, they were coated with a PEEK/45S5 bioactive glass composite by electrophoretic deposition, to be finally sintered at 350oC for 1h. The coatings homogeneity, infiltration efficiency, adhesion and cracking, were studied in order to establish correlations with processing conditions (time of deposition, applied voltage, composition, concentration and stability of the colloidal suspension). Detailed structural characterization of the coatings was performed (SEM and XRD), besides the contact angle and contact profilometry testing. Additional mechanical and chemical insights were achieved by evaluating both the tribo-mechanical (instrumented microindentation and micro-scratch testing) and electrochemical behaviors (potentiodynamic polarization and in vitro corrosion tests in SBF). All these results allowed us to determine the optimal balance of properties for a porous substrate (space holder of 250-355μm) with a coating obtained for 65 V, 2 min, 6 mm (distance between electrodes), 10 g/L bioactive glass and 20 g/l PEEK. The high adhesion estimated between the bioactive/biopolymer coatings and the porous titanium substrates (excellent infiltration) suggest that this new biocomposite is a good candidate for load-bearing applications.
Powder Consolidation of Titanium and Titanium Alloys by a Powder Compact Forging Process
Authors: Jia Ming Tu , Gabbitas Brian
Published: August 2016

Powder compact forging in combination with induction sintering, a field assisted sintering technique (FAST), was used to produce commercially pure (CP) Ti and Ti-13V-11Cr-3Al parts. Green powder compacts with high relative density were manufactured by cold compaction and warm compaction, respectively. During the powder compact forging process, CP titanium powder was consolidated completely to produce a near net shaped top cover for a diving helmet with full density and good mechanical properties. Also, a Ti-13V-11Cr-3Al alloy was fully consolidated into a cylinder using blended elemental powders. As a comparison, raw titanium powder with different oxygen contents was used to make a Ti-13V-11Cr-3Al powder compact forging. Using a starting powder with low oxygen content, a forged cylinder with good mechanical properties was produced.