The Positive Effect of Hydrogen Alloying on the Phase Tailoring and Mechanical Properties of Sintered Ti-13Nb SMAs

2019 ◽  
Vol 50 (11) ◽  
pp. 5525-5532
Author(s):  
Z. Xu ◽  
B. Yuan ◽  
Y. Gao
2016 ◽  
Vol 2016 ◽  
pp. 1-10 ◽  
Author(s):  
Haoliang Huang ◽  
Guang Ye

In this research, self-healing due to further hydration of unhydrated cement particles is taken as an example for investigating the effects of capsules on the self-healing efficiency and mechanical properties of cementitious materials. The efficiency of supply of water by using capsules as a function of capsule dosages and sizes was determined numerically. By knowing the amount of water supplied via capsules, the efficiency of self-healing due to further hydration of unhydrated cement was quantified. In addition, the impact of capsules on mechanical properties was investigated numerically. The amount of released water increases with the dosage of capsules at different slops as the size of capsules varies. Concerning the best efficiency of self-healing, the optimizing size of capsules is 6.5 mm for capsule dosages of 3%, 5%, and 7%, respectively. Both elastic modulus and tensile strength of cementitious materials decrease with the increase of capsule. The decreasing tendency of tensile strength is larger than that of elastic modulus. However, it was found that the increase of positive effect (the capacity of inducing self-healing) of capsules is larger than that of negative effects (decreasing mechanical properties) when the dosage of capsules increases.


2021 ◽  
Vol 316 ◽  
pp. 1019-1024
Author(s):  
O. A. Ignatova ◽  
A. A. Dyatchina

The paper presents the studies’ results of chemical composition, structure, and physico-mechanical properties of high-calcium ashes from the Kansk-Achinsk coals (2017-2019 selection). It was found that ash has a complex poly-mineral composition and contains hydraulically active minerals and oxides of СаОfr, β-C2S, CA, C3A, C4AF, C2F, CaSO4. According to the content of CaOfr, MgO does not meet standards’ requirements. The uniformity of the volume change is maintained by the composition with 50% of cement. The structure and hardening kinetics of ash and ash-cement stone compositions, obtained from the test of normal density, were analyzed. It was established that the hardening of compositions with ash from the Kansk-Achinsk coals was largely influenced by ash minerals. An equivalent amount of cement in composite binders cannot be replaced. In order to obtain a positive effect, compositions with ash instead cement of no more than 30% and a part of fine aggregate, without exceeding the ratio of ash: cement = 1: 1, should be used.


Author(s):  
K. Bobzin ◽  
W. Wietheger ◽  
J. Hebing ◽  
L. Gerdt ◽  
H. Krappitz ◽  
...  

Abstract Ni-based brazing coatings with tungsten or chromium carbides are used for wear and corrosion protection in various applications. Steam turbine blades especially present a highly stressed application in which in particular the resistance to erosion and corrosion is essential. Therefore, novel tape architectures of brazed coatings have been developed and investigated within this study. In contrast to the use of powders, the application by means of tapes offers a high potential with regard to later use in industry due to the reproducible handling and automation. In this work, different coating systems were successfully deposited by means of vacuum brazing on X12CrNiMo-12 steel substrate. In order to achieve a sufficient fracture toughness of the coatings, pure nickel powder was added to the tapes. The influence of this additive on the mechanical properties was analyzed by means of three-point bending tests. A positive effect has been observed when adding a volume fraction of φ(Ni) = 25% of nickel, increasing the flexural strength up to σf = 580 MPa. Furthermore, the surface hardness of the coating has been analyzed depending on coating architecture and post-deposition treatment by grinding.


2001 ◽  
Vol 10 (2) ◽  
pp. 096369350101000 ◽  
Author(s):  
D. Levitus ◽  
S. Kenig ◽  
M. Kazanci ◽  
H. Harel ◽  
G. Marom

The effect of the transcrystalline layer on the longitudinal properties of unidirectional polyethylene/polyethylene (PE/PE) composites was studied. Two sets of PE/PE composites were prepared by quenching and by isothermal crystallisation, respectively, using a wide range of fibre volume fractions. Quenching and isothermal crystallisation were expected, respectively, to prevent or to induce generation of a highly ordered transcrystalline layer. The experimental results showed that isothermal crystallisation produced a substantial positive effect on both the longitudinal strength and modulus, which was attributed to transcrystallinity.


FLORESTA ◽  
2005 ◽  
Vol 35 (1) ◽  
Author(s):  
Teresa María Suirezs

Este trabajo tuvo por objetivo, estudiar el comportamiento de las propiedades físicas y mecánicas de la madera de Pinus taeda L. impregnada por vacío-presión con preservador CCA (CrO3; CuO; As2O5) con tres retenciones, 5, 10 y 15 kg/m3. El proceso de impregnado se realizó, por el método Burnett, aplicándose presión y vacío de 7 kg/m2 y – 0,5 kg/m2 respectivamente. Los ensayos de las propiedades físicas y mecánicas se determinaron según lo establecen, las Normas técnicas IRAM (Instituto Argentino de Racionalización de Materiales), ASTM (American Society for Testing and Materials) y DIN (Deutsche Industrie Norm). Las propiedades físicas como ser los pesos específicos aparentes no son afectadas por las retenciones de CCA en la madera. Las contracciones tanto en el sentido tangencial como radial en las maderas impregnadas son menores. Las propiedades mecánicas de resistencia a la flexión estática, compresión paralela a las fibras, tracción perpendicular a las fibras, disminuyen levemente sus valores promedios con respecto a la madera sin impregnar, pero estas diferencias no son estadísticamente significativas, para 95 % de confianza. La impregnación ha producido un efecto positivo en la dureza Janka transversal y en el corte paralelo a las fibras tangencial siendo estas diferencias estadísticamente significativas. Behaviour of the wood of Pinus taeda impregnated with Chrome, Copper, Arsenic (CCA) Abstract The physical and mechanical properties of the wood of Pinus taeda L. without impregnating and impregnating by empty - pressure with preserving CCA (Chrome, Copper, Arsenic) with three retentions, 5, 10 and 15 kg/m3 have been determined and analysed. The impregnation was accomplished in an autoclave applying the Burnett method. The physical and mechanical properties were determined according to the following technical Procedures; IRAM (Argentine Institute for Rationalization of materials), ASTM (American Society for Testing and Material) and DIN (Deutsche Industrie Norm). The results indicate that the specific weights of samples containing different percentages of humidity was not affected by the retentions of CCA in the wood. The shrinkage both in the tangential and radial directions in the impregnated samples were smaller in the impregnated sample. The mechanical resistance to statics flexion, compression parallel to the fibers, traction perpendicular to the fibers, hardness tangential and radial Janka and paralell radial cut, do not show statistically meaningful differences between impregnated and not impregnated samples; however the treatment has produced a positive effect in the hardness transverse Janka and in the parallel cut to the tangential fibers.


2020 ◽  
Vol 1011 ◽  
pp. 151-157
Author(s):  
Sergey Khutorskoy ◽  
Denis Emelyanov ◽  
Alexander Matvievsky ◽  
Vasiliy Smirnov

The study results of the calcareous composites made with the use of activated mixing water are presented. Quicklime and slaked lime are used as lime binders. The mixing water was activated by the electric current and magnetic field in various modes. The effect of water activation on the physical and mechanical properties of slaked and quicklime composites and the resistance to the effects of the biological environment are studied. The water for mixing electromagnetic treatment effectiveness analysis is presented. The increase in the density of materials based on lime, trapped in activated water using ultrasound tests is proven. It was found that the mixing water activation affects the structure formation of composites and, under certain activation conditions, leads to an increase in such physical and mechanical parameters as strength and hardness. The positive effect of the mixing water activation on the lime-based materials’ resistance to microbial growth has been established, and the decrease in the growth of composites based on quicklime and slaked lime has been proved.


Polymers ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 1391 ◽  
Author(s):  
Viktor Kolář ◽  
Miroslav Müller ◽  
Rajesh Mishra ◽  
Anna Rudawska ◽  
Vladimír Šleger ◽  
...  

The paper is focused on the research of the cyclic loading of hybrid adhesive bonds based on eggshell microparticles in polymer composite. The aim of the research was to characterize the behavior of hybrid adhesive bonds with composite adhesive layer in quasi-static tests. An epoxy resin was used as the matrix and microparticles of eggshells were used as the filler. The adhesive bonds were exposed to cyclic loading and their service life and mechanical properties were evaluated. Testing was performed by 1000 cycles at 5–30% (165–989 N) and 5–70% (165–2307 N) of the maximum load of the filler-free bond in the static test. The results of the research show the importance of cyclic loading on the service life and mechanical properties of adhesive bonds. Quasi-static tests demonstrated significant differences between measured intervals of cyclic loading. All adhesive bonds resisted 1000 cycles of the quasi-static test with an interval loading 5–30%. The number of completed quasi-static tests with the interval loading 5–70% was significantly lower. The filler positively influenced the service life of adhesive bonds at a higher amount of quasi-static tests, i.e., the safety of adhesive bonds increased. The filler had a positive effect on adhesive bonds ABF2, where the strength significantly increased up to 20.26% at the loading of 5–30% against adhesive bonds ABF0. A viscoelasticity characteristic (creep) of the adhesive layer occurred at higher values of loading, i.e., between loading 5–70%. The viscoelasticity behavior did not occur at lower values of loading, i.e., between loading 5–30%.


Author(s):  
Yuan Li ◽  
Ning Hu ◽  
Takashi Kojima ◽  
Takaomi Itoi ◽  
Tomonori Watanabe ◽  
...  

The unique properties of carbon nanotube (CNT) have made it very attractive as reinforcement in polymer nanocomposites in the hope of effectively improving the mechanical properties. In order to explore the effects of three appealing influencing factors, i.e., acid treatment, pressured curing, and liquid rubber (LR) on mechanical properties of nanocomposites, tensile tests, and single-edge notched bending (SENB) tests are carried out for four types of CNT-reinforced nanocomposites. Compared with type I of nanocomposites using pristine multiwalled carbon nanotube (MWCNT) as reinforcement for epoxy, which are termed as Epoxy/MWCNT, type II of Epoxy/MWCNT-COOH nanocomposites with acid-treated MWCNTs as reinforcement, show obvious improvement on tensile properties and fracture toughness. This positive effect of acid treatment can be attributed to better dispersion of CNTs and stronger interface based on the corresponding fracture surfaces. For type III of P-Epoxy/MWCNT-COOH nanocomposites under pressured curing, although the voids in samples are decreased effectively and the interface is strengthened, there is no expected positive results because of severe CNTs agglomeration. For type IV of P-Epoxy/LR/MWCNT-COOH nanocomposites, addition of LR results in at least around a threefold increase in fracture toughness compared with that of P-Epoxy/MWCNT-COOH, indicating the amazing effect of LR. The present work provides much more choices for fabricating specific CNT-reinforced nanocomposites with desired properties by reasonably combining proper fabrication conditions including acid treatment, pressured curing, liquid rubber with polymer matrix, and reinforcement loading.


2021 ◽  
Vol 71 (342) ◽  
pp. e245
Author(s):  
S. Juradin ◽  
I. Netinger-Grubeša ◽  
S. Mrakovčić ◽  
D. Jozić

This paper deals with the possibility of the improvement of pervious concrete properties by incorporation of different types of fibres and studies the effect of short duration vibration of pervious concrete properties in comparison with compaction with wooden lath and hammer. Ten mixtures of pervious concrete were prepared, five of which were compacted with wooden lath and hammer and five by short duration vibration. Density, porosity, permeability and mechanical properties were tested for in hardened pervious concrete specimens. It was concluded that mixtures compacted by short duration vibration had better mechanical properties due to the formation of a viscous layer at the contact surface between the aggregate grain and the cement matrix during the compaction, as well as pore-related properties. The addition of fibres negatively affected porosity and permeability but generally improved mechanical properties of concrete. The positive effect of fibre addition was more emphasised in cases of vibrated mixtures.


2021 ◽  
Vol 1205 (1) ◽  
pp. 012017
Author(s):  
I Khongova ◽  
I Chromkova ◽  
V Prachar

Abstract The waste tire textile fibers from tires are generated as a by-product and are classified as special waste. To avoid landfilling and incineration of this waste, it is necessary to focus on its further use. This article describes an experimental study of the use of waste tire textile fibers for plaster mixtures. Waste fibers were added in different amounts of 2.9%, 3.6%, and 4.3% related to the weight of cement, the effect of fibers on selected properties was monitored. The results of the experimental work show that the lower addition of waste fibers (2.9% and 3.6%) had a predominantly positive effect on mechanical properties. By exceeding of the optimal dose of fibers, the tested properties of the plasters got worse.


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