Expansion Properties Research Articles

Analysis of the thermal expansion and mechanical properties of laser cladding of Invar alloy

Analysis of the thermal expansion and mechanical properties of laser cladding of Invar alloy

Interplay between insertion of zeros and the complexity of Dedekind cuts

The topic of this paper is the study of the possibility of effective conversions between different representations of irrational numbers. We are interested in subrecursive computations, in which we disallow the use of unbounded search. It is well-known that the base expansion of an irrational number can be subrecursively computed from its Dedekind cut, but in the reverse direction this is not subrecursively possible. Thus it would be natural to try to understand how additional properties of the base expansion, such as the presence of specific patterns of zero digits, correlate with the complexity of the Dedekind cut. Our first result roughly states that if large parts of zero digits dominate over smaller parts of arbitrary digits and the base expansion has elementary complexity, then the Dedekind cut also has elementary complexity. Much more interesting is the case when one allows large parts of zero digits to alternate with large parts of arbitrary digits. We compare the complexity of the Dedekind cuts of an arbitrary irrational number and another irrational number, obtained by inserting long sequences of zero digits in its base expansion. We provide examples in which (1) both numbers have elementary Dedekind cuts, (2) the first number has complex Dedekind cut and elementary base expansion, but the second number has elementary Dedekind cut and (3) both numbers have complex Dedekind cuts and elementary base expansions. An open question remains, whether it is possible for the first number to have elementary Dedekind cut, while the second number has complex Dedekind cut.

Enhanced comprehensive performance of Y2O3-Al2O3-SiO2 glass filler for SiC brazing by Li2O additive

Effects of Li2O additive on the network structure, crystallization behavior, thermal expansion properties and wettability of Y2O3-Al2O3-SiO2 glass were investigated. The results showed that Li2O could depolymerize the network structure, decreasing the characteristic temperatures of glass. The coefficient of thermal expansion of glasses varied from 5.09×10−6 K−1 to 8.03×10−6 K−1 by changing the Li2O addition and heat treatment process. Meanwhile, Li2O inhibited the crystallization of high-melting phases, consequently improving the fluidity of molten glass. The glass with 3 wt% Li2O showed an excellent wettability on SiC ceramic with a contact angle of 18°, and a sound joint mainly consisted of glassy phase was obtained at 1430 ℃ for 30 min. The prepared joints exhibited a shear strength of 119.7±20.3 MPa, which is 5.4 times of that without Li2O. After 3 times of water-quenching from 1200 ℃, the joints remained 68.4% of its original strength, demonstrating graceful reliability.

Influence of Thermally Aged Underfill on Flip-Chip Packages

Underfill material plays a crucial role in flip-chip package reliability, thus it necessary to accurately understand the mechanical properties. The material itself is nonlinear and is dependent on degree of cure, temperature, strain rate and thermal aging, among others. In this work, two underfill materials were characterized for thermal expansion and viscoelastic properties over a wide temperature range. A second set of each material was thermally aged through flip-chip processing steps and 250 thermal cycles and then characterized. Temperature dependent thermal expansion and timetemperature dependent moduli curves were generated to represent each material type. These material models were then implemented into a nonlinear finite element model of a flip-chip package to evaluate package stress interaction through processing steps and thermal cycling. The influence that each underfill material had with and without thermal aging was analyzed with respect to typical package failure mechanisms.

Effect of Si alloying on the structural, thermal expansion, and magnetic properties of FeCoNiAlSix high-entropy alloys

Effect of Si alloying on the structural, thermal expansion, and magnetic properties of FeCoNiAlSix high-entropy alloys

Behavior of high strength reinforcing steel rebars after high temperature exposure: Tensile properties and bond behavior using pull-out and end beam tests

High strength reinforcing steel (HSRS) is increasingly being adopted in the construction industry in North America due to its high load-carrying capacity, yet their behavior relative to normal grade rebars under external hazard events such as fire exposure still need further research. In current work, the first goal is to investigate the residual tensile properties of different types of HSRS and normal rebars including ASTM A706, A615, A1035CS, and A1035CM with grades of 420, 550, and 690 before and after high temperatures (350 °C and 700 °C), that simulates residual capacity after different levels of fire exposure. The second goal is to explore the residual bond strength of these rebars using both pull-out and end-beam tests after heat exposure, facilitating a comparison among test methods and evaluating their reliability under fire hazard conditions. The tensile test results indicated insignificant changes in the mechanical properties of all rebars after 350 ℃ heat exposure. However, there was a significant reduction of more than 30% in both yield and ultimate strength after 700 ℃ heat exposure for high grades like grade 690 of ASTM A1035. Among all rebar types and grades, only grade 420 of ASTM A706 retained most of its ductility and strength, making it the most reliable rebar among those tested against fire hazards. In the bond tests, splitting failure was observed at both ambient and after 500 °C heat exposure. Heat exposure resulted in a 73% reduction in bond strength across all rebars for the pull-out tests, with no significant variations between rebar types. On the other hand, end-beam tests indicated a 12.6% average reduction in bond strength with a 9% improvement in bond behavior for ASTM A706 grade 420. However, for ASTM A1035 CS grade 690 and ASTM A706 grade 550 there were slight reductions in bond behavior, with decreases of 9% and 14%, respectively. Compared to the end-beam test, the pull-out test results in a significant reduction in bond strength due to its high dependency on excessive compressive strength reduction resulting in brittle splitting failure. Based on comparison with empirical models, it is recommended not to use models derived from pull-out tests to estimate bond strength, as they tend to overestimate it. Instead, empirical models based on end-beam tests are recommended, since they show consistency with test results. It should be noted that although the bond strength based on splitting failure is primarily dependent on concrete properties, changes were observed in the bond behavior among different rebars, which can be attributed to changes in friction at the interface due to morphological changes in the rebar surface after heat exposure, as well as potential variations in thermal expansion properties, which need further research.

Thermally expandable microspheres based on fully or partially bio‐based polymers

AbstractBio‐based or partially bio‐based thermally expandable microspheres (TEMs) were synthesized by suspension (co)polymerization of the bio‐based monomer α‐methylene‐γ‐valerolactone (MeMBL) together with acrylonitrile and/or methyl methacrylate to form expandable core/shell particles by encapsulating a hydrocarbon‐based blowing agent. The core/shell polymers were characterized with respect to their chemical structure, thermal expansion, and morphology. The obtained particles, TEMs, showed an increasing onset expansion temperature with increasing content of MeMBL owing to the high glass transition temperature of PMeMBL. As a result, bio‐based/partially bio‐based TEMs are achieved with high thermal stability and expansion properties which can be tailored for various applications.

Fluorescent probe effect of super-sensitive transition Dy3+ ions in the negative thermal expansion materials Sc2W3O12

Negative thermal expansion (NTE) materials have attracted significant attention for their distinctive thermal expansion properties and potential applications in various fields such as micro-electronic packaging, aerospace engineering, optics, and sensors. Despite significant advancements, the field continues to face numerous challenges, including scarcities in material types, unclear mechanisms underlying thermal shrinkage, response temperature far from room temperature, as well as limited potential for industrialization. In our work, we report a type of Sc2W3O12:Dy3+ luminescent material whereby the doped super-sensitizing rare earth ion Dy3+ can form luminescent centers within a specific crystal field environment, thereby extending the optical properties of NTE materials. With the temperature increasing, the emission of WO42− undergoes a red shift, and the yellow-to-blue (Y/B) ratio resulting from Dy3+ transitions increase, effectively illustrate the W–O bond spacing decreases. The effect of lattice shrinkage with increasing temperature is proved by the optical performance of luminescent ions in the NTE materials, gives rare earth ions the role of fluorescent probes in the process of negative thermal expansion. This also provides a novel strategy for the dynamic monitoring of lattice environments that vary with temperature.

Atomic Layer Deposition of ScF3 and ScxAlyFz Thin Films.

In this paper, we present an ALD process for ScF3 using Sc(thd)3 and NH4F as precursors. This is the first material made by ALD that has a negative thermal expansion over a wide-temperature range. Crystalline films were obtained at the deposition temperatures of 250-375 °C, with a growth per cycle (GPC) increasing along the deposition temperature from 0.16 to 0.23 Å. Saturation of the GPC with respect to precursor pulses and purges was studied at 300 °C. Saturation was achieved with Sc(thd)3, whereas soft saturation was achieved with NH4F. The thickness of the films grows linearly with the number of applied ALD cycles. The F/Sc ratio is 2.9:3.1 as measured by ToF-ERDA. The main impurity is hydrogen with a maximum content of 3.0 at %. Also carbon and oxygen impurities were found in the films with maximum contents of 0.5 and 1.6 at %. The ScF3 process was also combined with an ALD AlF3 process to deposit ScxAlyFz films. In the AlF3 process, AlCl3 and NH4F were used as precursors. It was possible to modify the thermal expansion properties of ScF3 by Al3+ addition. The ScF3 films shrink upon annealing, whereas the ScxAlyFz films show thermal expansion, as measured with HTXRD. The thermal expansion becomes more pronounced as the Al content in the film is increased.

Anisotropic thermal expansion and themomechanic properties of α-phase group-VA monolayers

The theoretical investigations of anisotropic thermal expansion are quite few as the huge computational cost. In this work, a scheme of Taylor expansion for phonon free energy is introduced to investigate anisotropic thermal expansion, which can save lots of computational cost. The anisotropic thermal expansion and thermomechanic properties of α-phase group-VA monolayers (α-P, α-As, α-Sb and α-Bi) are investigated systematically by using the first-principles calculations. It is found all the four monolayers show remarkably anisotropic thermal expansion, and very different from each other. In α-As and α-Bi monolayers, remarkable negative thermal expansion appears along armchair direction. From α-P to α-Bi monolayer, the absolute value of linear thermal expansion coefficient becomes larger. In particular the linear thermal expansion coefficient of α-Bi is in terms of order of magnitude close to 10−4 K−1 at 300 K. The macroscopic Grüneisen parameters and elastic constants are also investigated to unveil the underlying physical mechanisms.

Chameleon inspired high-temperature thermochromic traffic light type photonic crystal sensors toward early fire detection and visual sensing

Fire detection plays a crucial role in maintaining the safety of people’s lives and property. However, most early fire detectors are designed to monitor the current or voltage changes of the sensing materials, which require external power supplies. It is still a challenge to make rapid and accurate noncontact early fire detection in precombustion due to the lack of reliable alarm signals. Herein, inspired by the discoloration of chameleon skin, we developed an early fire warning sensor (EFWS) by coating photonic crystals (PCs) on a plastic sheet with thermal expansion properties. Monodispersed zinc sulfide (ZnS) was coated on the plastic sheet as abnormal detection component for EFWS. Combined with the intelligent image recognition algorithm, the EFWS was designed and gave warnings for 0.9 s at 260 °C. For the first time, a photonic crystal-based non-contact real-time monitoring EFWS in precombustion is developed. The sensing material can be directly pasted on the surface of the detected equipment, and combined with existing surveillance cameras in the detection area, early warning of fires can be achieved. The EFWS system can be used in non-open fire alarms for aircraft, buildings, electrical appliances, substations, and other places in the future.

CaSSiDI: novel single-cell “Cluster Similarity Scoring and Distinction Index” reveals critical functions for PirB and context-dependent Cebpb repression

PirB is an inhibitory cell surface receptor particularly prominent on myeloid cells. PirB curtails the phenotypes of activated macrophages during inflammation or tumorigenesis, but its functions in macrophage homeostasis are obscure. To elucidate PirB-related functions in macrophages at steady-state, we generated and compared single-cell RNA-sequencing (scRNAseq) datasets obtained from myeloid cell subsets of wild type (WT) and PirB-deficient knockout (PirB KO) mice. To facilitate this analysis, we developed a novel approach to clustering parameter optimization called “Cluster Similarity Scoring and Distinction Index” (CaSSiDI). We demonstrate that CaSSiDI is an adaptable computational framework that facilitates tandem analysis of two scRNAseq datasets by optimizing clustering parameters. We further show that CaSSiDI offers more advantages than a standard Seurat analysis because it allows direct comparison of two or more independently clustered datasets, thereby alleviating the need for batch-correction while identifying the most similar and different clusters. Using CaSSiDI, we found that PirB is a novel regulator of Cebpb expression that controls the generation of Ly6Clo patrolling monocytes and the expansion properties of peritoneal macrophages. PirB’s effect on Cebpb is tissue-specific since it was not observed in splenic red pulp macrophages (RPMs). However, CaSSiDI revealed a segregation of the WT RPM population into a CD68loIrf8+ “neuronal-primed” subset and an CD68hiFtl1+ “iron-loaded” subset. Our results establish the utility of CaSSiDI for single-cell assay analyses and the determination of optimal clustering parameters. Our application of CaSSiDI in this study has revealed previously unknown roles for PirB in myeloid cell populations. In particular, we have discovered homeostatic functions for PirB that are related to Cebpb expression in distinct macrophage subsets.

Experimental Study on Modification of Grouting Material for Joints of Prefabricated Buildings

In order to apply grouting material to the joints of fabricated buildings and make it meet the performance demands of low shrinkage, strong bond, and high toughness of joint materials for prefabricated buildings, the expansion agent (EA), neoprene latex (NL), and rubber particles (RP) were used to modify the grouting material, and the effects of different dosages of the three components on the working performance, mechanical properties, and expansion or shrinkage properties of the grouting material were investigated. The results show that the EA decreases the flexural strength-to-compressive strength ratio (FCR) of the grouting material and enhances the vertical expansion rate and bond strength. The dosage of EA and the curing conditions have a significant effect on the expansion rate of the hardened grouting material. The grouting material can still maintain its 0.0022% free expansion rate with a 7% EA dosage at 120 d. The NL significantly inhibits the vertical expansion of the fresh mortar but inhibits the drying shrinkage of the grouting material after hardening, improves the FCR and bond strength; the 7 d bond strength under a 5% NL dosage can reach 4.27 MPa. The RP inhibits the vertical expansion of the fresh mortar and the drying shrinkage after mortar hardening; with the increase of its dosage, the bond strength of the grouting material increases first and then decreases, the 28 d FCS of the grouting material peaked at 0.173 at 10% dosage.

Effects of enzyme addition on the expansion properties and dietary fiber composition of barley flour-blended breads

Effects of enzyme addition on the expansion properties and dietary fiber composition of barley flour-blended breads

A note on the width of sparse random graphs

AbstractIn this note, we consider the width of a supercritical random graph according to some commonly studied width measures. We give short, direct proofs of results of Lee, Lee and Oum, and of Perarnau and Serra, on the rank‐ and tree‐width of the random graph when for constant. Our proofs avoid the use of black box results on the expansion properties of the giant component in this regime, and so as a further benefit we obtain explicit bounds on the dependence of these results on . Finally, we also consider the width of the random graph in the weakly supercritical regime, where and . In this regime, we determine, up to a constant multiplicative factor, the rank‐ and tree‐width of as a function of and .

Inflation alternative via the gravitational field of a singularity

We explore the scenario that the observable Universe emerged from the vicinity of a negative mass ring singularity, and all content of the Universe travels at the same group velocity close to the speed of light on a geodesic trajectory along the axis of rotation of the singularity. In appropriate coordinate parametrization and evaluated on the trajectory, we find that the metric tensor in the vicinity of the trajectory exhibits a conformal scale factor a(η) with contraction and subsequent expansion properties that solve the horizon problem. We then introduce a static flow of gravitating radiation along the trajectory (perturbatively with respect to the mass scale of the singularity) to model a homogeneous radiation dominated Universe. Solving the Einstein field equations with a physically motivated ansatz of metric perturbation then reveals that the effective conformal scale factor indeed grows asymptotically with the same power law as expected in a conventional radiation dominated Universe.

Blood volume and hemodynamics during treatment of major hemorrhage with Ringer solution, 5% albumin, and 20% albumin: a single-center randomized controlled trial

BackgroundVolume replacement with crystalloid fluid is the conventional treatment of hemorrhage. We challenged whether a standardized amount of 5% or 20% albumin could be a viable option to maintain the blood volume during surgery associated with major hemorrhage. Therefore, the aim of this study was to quantify and compare the plasma volume expansion properties of 5% albumin, 20% albumin, and Ringer-lactate, when infused during major surgery.MethodsIn this single-center randomized controlled trial, fluid replacement therapy to combat hypovolemia during the hemorrhagic phase of cystectomy was randomly allocated in 42 patients to receive either 5% albumin (12 mL/kg) or 20% albumin (3 mL/kg) over 30 min at the beginning of the hemorrhagic phase, both completed by a Ringer-lactate replacing blood loss in a 1:1 ratio, or Ringer-lactate alone to replace blood loss in a 3:1 ratio. Measurements of blood hemoglobin over 5 h were used to estimate the effectiveness of each fluid to expand the blood volume using the following regression equation: blood loss plus blood volume expansion = factor + volume of infused albumin + volume of infused Ringer-lactate.ResultsThe median hemorrhage was 848 mL [IQR: 615–1145]. The regression equation showed that the Ringer-lactate solution expanded the plasma volume by 0.18 times the infused volume while the corresponding power of 5% and 20% albumin was 0.74 and 2.09, respectively. The Ringer-lactate only fluid program resulted in slight hypovolemia (mean, − 313 mL). The 5% and 20% albumin programs were more effective in filling the vascular system; this was evidenced by blood volume changes of only + 63 mL and − 44 mL, respectively, by long-lasting plasma volume expansion with median half time of 5.5 h and 4.8 h, respectively, and by an increase in the central venous pressure.ConclusionThe power to expand the plasma volume was 4 and almost 12 times greater for 5% albumin and 20% albumin than for Ringer-lactate, and the effect was sustained over 5 h. The clinical efficacy of albumin during major hemorrhage was quite similar to previous studies with no hemorrhage.Trial registration: ClinicalTrials.gov NCT05391607, date of registration May 26, 2022.

Effects of the combination of phenolic-resin impregnation and heat treatment on physical, mechanical and decay resistance of Taxodium hybrid “Zhongshanshan” wood

ABSTRACT This study aimed to evaluate the influence of cooperative modification treatments and treatment sequencing on the properties of treated fast-growing wood. Two integrated treatment methods including, impregnation with Phenol-Formaldehyde resin followed by heat treatment (PF-HT), and heat treatment antecedent to impregnation with Phenol-Formaldehyde resin (HT-PF) were applied on Taxodium hybrid “Zhongshanshan” wood. Comprehensive characterization was undertaken, investigating micro-morphology, chemical structure, mechanical properties, shrinkage and expansion properties, and decay resistance before and after treatment. Results indicated that the weight percentage gain (WPG) of the HT-PF wood exceeded that of the PF-HT wood, and the WPG of the former displayed an ascending tendency with increasing heating temperature, reaching a final difference of 10%. For instance, the modulus of elasticity of the HT-PF wood was 18% higher than that of the PF-HT wood in the bending test at a temperature of 215°C. Throughout the dynamic water adsorption test, both the hydrated water percentage and the dissolved water percentage of PF-HT wood were lower than those of PF-HT wood. After 3 months of exposure to brown-rot fungi, both HT-PF wood and PF-HT wood achieved a high level of decay resistance.

Anisotropy of microstructure, mechanical properties and thermal expansion in Invar 36 alloy fabricated via laser powder bed fusion

Invar 36 is a renowned iron-nickel alloy with an ultra-low coefficient of thermal expansion (CTE), which is widely used in aerospace and precision instruments. Laser powder bed fusion (LPBF) as a prevalent metal additive manufacturing technique could break through the limitations of traditional processes, such as low material utilization and difficulties in forming complex structures. In this work, Invar 36 alloy specimens were fabricated via LPBF process in 0° (H0 specimen), 45° (D45 specimen), and 90° (V90 specimen) build orientations. The microstructure, tensile properties, thermal expansion, and magnetic properties of the three orientations specimens were comprehensively investigated, and the anisotropy of microstructure, yield strength and CTE were analyzed. The V90 specimen exhibited the highest elongation (62.70%), while the D45 specimen owned the highest yield strength (496 MPa). The anisotropic mechanical properties can be attributed to variations in dislocation density, grain size, and intrinsic yield strength. The CTE of LPBF-fabricated Invar 36 alloy specimens were all lower than that of traditional manufacturing process at all temperature ranges. Since CTE is more related to magnetic properties, not sensitive to microstructure, the anisotropy of CTE is not significant in three build orientations. This study has significant implications to produce Invar 36 alloy devices with exceptional properties and 3D dimensional stability via the LPBF process.

Preparation, characterization and composition optimization design of laser powder bed fusion continuously graded Invar36/316L stainless steel alloys

It is of great significance for designing different material compositions and batch experimental research via using additive manufacturing. In this work, Invar36 and 316L stainless steel (SS) are used as raw materials, and a specially designed powder distribution system in a laser powder bed fusion (LPBF) equipment is used to prepare continuous gradient alloys (CGAs) of Invar36/316L SS. The effects of microstructure and properties variations when the ratio of two compositions of Invar36 and 316L SS are systematically studied. It is found that the grain size and morphology of the melt pool would vary with the composition, but there is no significant difference in the phase distribution. In addition, localized areas of CGAs show similar or even better mechanical properties, thermal expansion properties, or corrosion resistance than the two materials themselves. When the percentage of Invar36 content is 70% - 80%, the microstructure and grain distribution of the samples are relatively uniform, and the tensile strength and corrosion resistance of the material are greatly improved, while the coefficient of thermal expansion does not increase significantly. The results of this work provide a practical path for the composition design and high throughput experiments of multiple materials.