Cracks on ETICS along thermal insulation joints: case study and a pathology catalogue

2016 ◽  
Vol 34 (1) ◽  
pp. 57-72 ◽  
Author(s):  
Sara Stingl de Freitas ◽  
Vasco Peixoto de Freitas
Keyword(s):  
Thermal Expansion ◽  
Thermal Expansion Coefficient ◽  
Thermal Insulation ◽  
Expansion Coefficient ◽  
Mechanical Behaviour ◽  
Climatic Conditions ◽  
Insulation Material ◽  
Content Type

Purpose – The purpose of this paper is to present a case study of cracks on external thermal insulation composite systems (ETICS) along the thermal insulation joints and the information available on the building pathology catalogue – PATORREB. The aim is to establish the methodology to study the cause of the pathology observed on a building which is located on the interior of Portugal based on in situ probing together with the analysis of hygrothermal and mechanical behaviour. Design/methodology/approach – An in situ analysis was performed to assess the causes. The hygrothermal dynamic behaviour of the wall was analysed with a numerical simulation advanced tool considering the climatic conditions, the characteristics of the thermal insulation plates as well as the support and finishing layer properties. Moreover, a qualitatively analysis of the mechanical behaviour, based on the bonding process, thermal insulation and exterior rendering properties was performed. Findings – It was concluded that the insulation properties – thermal expansion coefficient and stiffness, the thermal expansion coefficient of the exterior rendering, together with adverse climatic conditions were critical for the appearance of cracks along the plate joints, particularly with spot bonding. The expansion and retraction stresses and the restrained movements of the components can result in bending moments, especially when the insulation material has a high stiffness value, which will create the crack on the rendering system. Originality/value – A combination between a hygrothermal and mechanical analysis of an ETICS pathology concerning the appearance of cracks with a subsequent integration into a building pathology catalogue.

In Situ Formation of Mullite-Al2O3 Refractory Ceramic from Al-Matrix Mixtures

2014 ◽  
Vol 602-603 ◽  
pp. 628-631
Author(s):  
Xing Yong Gu ◽  
Ping Li ◽  
Wei Xia Dong ◽  
Ting Luo
Keyword(s):  
Thermal Expansion ◽  
Bulk Density ◽  
Thermal Expansion Coefficient ◽  
Expansion Coefficient ◽  
Bending Strength ◽  
Potential Effect ◽  
Apparent Porosity ◽  
Mullite Phase ◽  
Two Samples

Two types of mullite-Al2O3 composites were designed and sintered in situ from different composition containing Al composites e.g. kaolin, alumina hydroxide and calcined bauxite etc, and auxiliary additives. The phase composition and microstructure were studied using X-ray diffraction (XRD) and scanning electron microscope (SEM) techniques. Bulk density, apparent porosity, thermal expansion coefficient and bending strength were also measured. The two samples exhibited XRD reflections characteristic of alumina and mullite phases. The amount of these phases depended on starting batch compositions, and reaction of starting and auxiliary materials together to form mullite. Because of in-situ formation of mullite fiber, the bulk density and bending strength were improved and apparent porosity was decreased for the composites with uniform microstructure. The presence of high mullite phase was found to decrease the thermal expansion coefficient. The potential effect of these morphologies and phase on properties was discussed. These mullite-Al2O3 composite was expected to have major applications in the areas of refractory material.

Thermal expansion coefficient of carbon-supported Pt nanoparticles: In-situ X-ray diffraction study

2017 ◽  
Vol 254 (5) ◽  
pp. 1600695 ◽  
Author(s):  
I. N. Leontyev ◽  
A. A. Kulbakov ◽  
M. Allix ◽  
A. Rakhmatullin ◽  
A. B. Kuriganova ◽  
...  
Keyword(s):  
Thermal Expansion ◽  
Diffraction Study ◽  
Thermal Expansion Coefficient ◽  
Expansion Coefficient ◽  
Pt Nanoparticles ◽  
X Ray Diffraction ◽  
X Ray

scholarly journals Effect of Thermal Stresses Formed during Air Annealing of Amorphous Lanthanum Cuprate Thin Films Deposited on Silicon Substrate

Coatings ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 613 ◽  
Author(s):  
Nolwenn Tranvouez ◽  
Philippe Steyer ◽  
Annie Malchère ◽  
Pascal Boulet ◽  
Fabien Capon ◽  
...  
Keyword(s):  
Thin Films ◽  
Thermal Expansion ◽  
Thermal Expansion Coefficient ◽  
Expansion Coefficient ◽  
Thermal Stresses ◽  
Environmental Scanning Electron Microscopy ◽  
X Ray Diffraction ◽  
X Ray ◽  
Lift Off

Amorphous thin films of La–Cu–O deposited by magnetron sputtering have been annealed at different temperatures and in situ analyzed by X-ray diffraction. These experiments were useful to determine the crystallization temperature and to follow the crystallization process of the film. The in situ annealing X-ray diffraction analyses have been also used to determine the thermal expansion coefficient of La2CuO4 thin film. The estimated value is close to that obtained for a commercial powder. The thermal expansion coefficient value with additional environmental scanning electron microscopy observations explains the delamination origin that occurs during the annealing before the crystallization step. The buckling and delamination of the film observed is caused by the thermal expansion coefficient mismatch of the film and the substrate. During the heating step, the mismatch generates compressive stress at the film/substrate interface, causing the film to lift off and crack in the typical way.

Influence of substrate characteristics on residual stress of SLMed Inconel 718

2019 ◽  
Vol 25 (4) ◽  
pp. 792-799
Author(s):  
Yong Cheng ◽  
Zhongxu Xiao ◽  
Haihong Zhu ◽  
Xiaoyan Zeng ◽  
Guoqing Wang
Keyword(s):  
Thermal Conductivity ◽  
Residual Stress ◽  
Thermal Expansion ◽  
Temperature Gradient ◽  
Thermal Expansion Coefficient ◽  
Expansion Coefficient ◽  
Inconel 718 ◽  
Compression Stress ◽  
Content Type ◽  
Influence Of Substrate

Purpose Selective laser melting (SLM) is a promising additive manufacturing technology in the field of complex parts’ fabrication. High temperature gradient and residual stress are vital problems for the development of SLM technology. The purpose of this paper is to investigate the influence of substrate characteristics on the residual stress of SLMed Inconel 718 (IN718). Design/methodology/approach The SLMed IN718 samples were fabricated on the substrates with different characteristics, including pre-compression stress, materials and pre-heating. The residual stress at the center of the top surface was measured and compared through Vickers micro-indentation. Findings The results indicate that the residual stress reduces when the substrate contains pre-compression stress before the SLM process starts. Both substrate thermal expansion coefficient and thermal conductivity affect the residual stress. In addition to reducing the difference of thermal expansion coefficient between the substrate and the deposited material, the substrate with low thermal conductivity can also decrease the residual stress. Substrate pre-heating at 150°C reduces nearly 42.6 per cent residual stress because of the reduction of the temperature gradient. Originality/value The influence of substrate characteristics on the residual stress has been studied. The investigation results can help to control the residual stress generated in SLM processing.

Preparation and Characteristics of ZrO2/ZrW2O8 Composites with Low Thermal Expansion

2018 ◽  
Vol 768 ◽  
pp. 87-91
Author(s):  
Jin Ping Li ◽  
Cheng Yang ◽  
Yu Han Li ◽  
Song He Meng
Keyword(s):  
Thermal Expansion ◽  
Thermal Expansion Coefficient ◽  
Expansion Coefficient ◽  
Ceramic Matrix Composites ◽  
Ceramic Matrix ◽  
Cold Isostatic Pressing ◽  
Raw Material ◽  
Matrix Composites ◽  
Low Thermal Expansion

The ZrO2/ZrW2O8 ceramic matrix composites have been prepared by the two different processes: (1) ZrO2 and ZrW2O8 powders were mixed directly as raw material, then compacted by cold isostatic pressing under 200MPa, and finally, the ceramic matrix composites with low thermal expansion can be prepared by use of heat-pressing sintering or atmospheric sintering at temperature 1215oC. (2) ZrO2 (with excess mass) and WO3 powers were mixed as raw material, then compacted by cold isostatic pressing under 200MPa, and finally, the ZrO2/ZrW2O8 ceramic matrix composites can be made by use of heat-pressing sintering or atmospheric sintering at temperature 1215 oC after ZrW2O8 were synthesized by in-situ reaction of ZrO2 and WO3 powders at the same temperature. The microstructure, density, ZrW2O8 decomposition degree and the thermal expansion coefficient were compared among the sintered samples fabricated by the above two different methods, and affected by the different process parameters. The results show that the ceramic matrix composites with low thermal expansion are really composed of ZrO2, ZrW2O8 and WO3, and their relative densities are all more than 95%. Compared with the composites prepared by in-situ reaction, the densities, ZrW2O8 decomposition degree and the thermal expansion coefficient of the composites made by direct mixing are higher, less and smaller, respectively.

Temperature-driven directional coalescence of silver nanoparticles

2016 ◽  
Vol 23 (3) ◽  
pp. 718-728 ◽  
Author(s):  
Shi Yan ◽  
Dongbai Sun ◽  
Yu Gong ◽  
Yuanyuan Tan ◽  
Xueqing Xing ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Thermal Stability ◽  
Silver Nanoparticles ◽  
Thermal Expansion ◽  
Thermal Expansion Coefficient ◽  
Expansion Coefficient ◽  
Temperature Dependent ◽  
X Ray ◽  
Nanoparticle Growth

Silver nanoparticles were synthesized with a chemical reduction method in the presence of polyvinylpyrrolidone as stabilizing agent. The thermal stability behavior of the silver nanoparticles was studied in the temperature range from 25 to 700°C. Thermal gravimetric analysis was used to measure the weight loss of the silver nanoparticles. Scanning electron microscopy and high-resolution transmission electron microscopy were used to observe the morphology and the change in shape of the silver nanoparticles.In situtemperature-dependent small-angle X-ray scattering was used to detect the increase in particle size with temperature.In situtemperature-dependent X-ray diffraction was used to characterize the increase in nanocrystal size and the thermal expansion coefficient. The results demonstrate that sequential slow and fast Ostward ripening are the main methods of nanoparticle growth at lower temperatures (<500°C), whereas successive random and directional coalescences are the main methods of nanoparticle growth at higher temperatures (>500°C). A four-stage model can be used to describe the whole sintering process. The thermal expansion coefficient (2.8 × 10−5 K−1) of silver nanoparticles is about 30% larger than that of bulk silver. To our knowledge, the temperature-driven directional coalescence of silver nanocrystals is reported for the first time. Two possible mechanisms of directional coalescence have been proposed. This study is of importance not only in terms of its fundamental academic interest but also in terms of the thermal stability of silver nanoparticles.

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