Cladding Materials Research Articles

Revealing the role of hydrogen content on the mechanical behavior and cracking mechanisms of Zircaloy-4 under strain

The mechanical property of zirconium-alloy reactor cladding materials inevitably degrades because of hydrogen absorption and hydride precipitation. In this study, mechanical behavior and delayed hydrogen cracking (DHC) mechanisms of Zircaloy-4 alloys with a broad range of hydrogen contents were investigated. Scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), transmission electron microscopy (TEM), and a universal testing machine were jointly employed for this purpose. Results showed that the mechanical property of the hydrogenated specimen not only depended on the size and orientation of hydride, but also was affected by the continuity degree of the load-bearing matrix. The relevant microstructural observation indicated that the lower continuity degree of the load-bearing matrix, the less ductility of Zircaloy-4. More importantly, hydride phase transformation from δ-ZrH 1.5 to γ-ZrH occurred around the crack tip and reduced the local strain, while twinning just appeared at the crack bridging sites in the higher hydrogen-content specimens for changing the crystal orientation and mitigating the local stress concentration. Both those effects are expected to be potential mechanisms of the reappearing yield phenomenon because they are closely linked to dislocation movement. Additionally, based on the combination effect of crack blunting of γ-ZrH and the strain accommodation of twinning, the trend of crack propagation is delayed locally as expected. • The hydride phase transformation and twinning phenomenon around cracks were analyzed using EBSD. • The continuity of the load-bearing matrix profoundly influenced the mechanical properties of hydrided zircaloy-4. • The appearance and disappearance of yield-suppression phenomenon in hydrided zircaloy-4 were investigated. • Both γ-ZrH and twins are beneficial to delay the localized crack propagation.

Titanium clad plate forming: critical consideration and how different it is from solid titanium forming

Titanium offers exceptional corrosion resistance both in organic & inorganic acid media. Thus, it is a preferred material by various industries such as Oil and Gas refining, Petrochemical (PTA Plant) including Nickel refining by Hydrometallurgy. These equipment are operated at high temperature and pressure, necessitating the use of higher thickness for safety and efficient functioning. Therefore, use of solid titanium is not economical, and often substituted with explosion bonded Ti-Clad steel. Fabrication of certain components of this equipment like Dished heads are required to be made by forming with options of cold, warm or hot forming. Selection of forming method for Ti-clad steel component is often governed by its effect on Clad-Base metal bond integrity and reduction shear strength unlike other commonly used Stainless steel or Ni-based alloy clad material, wherein thickness of the base metal is major deciding factor. In case of Ti-Clad steels both cladding and base metal are not metallurgically compatible as well as differs significantly in their physical properties, forming temperature plays a crucial role. This paper describes the effect of various Dished heads forming methodology on integrity of clad plate. Also, it brings out how the Ti-clad steel forming is critical than the forming of solid Titanium.

Development of adaptive technologies for the operation of irrigation canals covered with a concrete canvas

The relevance of the study is to expand and obtain new theoretical knowledge on the application of adaptive technologies of irrigation canals operation depending on the type of facing materials, namely geosynthetic materials. The object of the study is a concrete canvas. The analysis included methods of empirical and experimental-theoretical level. The work considered and compared such cladding materials as geomembrane, bentonite mats and concrete cladding as a traditional cladding material. The given theoretical provisions of the work allow for the possibility of applying small mechanized equipment when carrying out works on cleaning the canal beds covered with concrete canvas from sediments.

Characterization and single track analysis of a metal-ceramic composite laser cladding over Ti6Al4V alloy

The present experimental investigation is dealt with the formation of composite cladding on Ti6Al4V alloy using laser melting and deposition (LMD) technique. The reinforcement consisting of ilmenite (Fe-TiO3), CeO2, La2O3, cubic boron nitride (cBN) and Ti6Al4V in different compositions ratio are considered as cladding materials to fabricate a dense composite clad surface. Single tracks are formed using 15.92 × 104 w/cm2 laser power density and three different laser scanning speeds of 200,400 and 600 mm/min to analyze the clad height, aspect ratio, dilution rate and average contact angle of the track. Further, area clads are fabricated for different powder compositions of the cladding materials. The clad layer thickness are found to be decreases with increase in laser scanning speed and rise in the percentage of ilmenite (Fe-TiO3). The formation of different microstructure in the clad as well as interface zone are observed. With the increase in the percentage composition of ilmenite with cerium and lanthanum leads to the refined and coarser grain microstructure with unique structure are found which enhance mechanical properties like wear and hardness of the clad. Some of the important microstructure like dendritic, lamellar, flower, grit type and long needle type are found on the clad surface. The formation of unique chemical compound such as Ti3O, La2O3, Ti2B5, LaTi21O38, Ce3B2N4, Fe4N, TiN, La3BO6, and Fe-TiO3 are observed through the XRD analysis. Micro hardness of the clad surface are found to be increases approximately five times to the substrate at the clad with the increase in percentage composition of RE element, but found to be decrease drastically as passing through the intersection zone due to intermixing phenomena of clad and the substrate. It is observed that with higher percentage composition of RE result decrease in the reduction of the coefficient of friction approximately thrice to that of the cladded sample as compare to base (Ti6Al4V), which improve the wear resistance of the clad material. However there are minor amount of defects like micro crack are found on the clad and wear at the disk are occurred due to ploughing and cutting observed through track analysis.

Carburization Kinetics of Zircalloy-4 and Its Implication for Small Modular Reactor Performance.

Carburization of cladding materials has long been a concern for the nuclear industry and has led to the restricted use of high-thermal conductivity fuels such as uranium carbides. With the rise of small modular reactors (SMRs) that frequently implement a graphite core-block, carburization of reactor components is once more in the foreground as a potential failure mechanism. To ensure commercial viability for SMRs, neutron-friendly cladding materials such as Zr-based alloys are required. In this work, the carburization kinetics of Zircaloy-4 (Zry-4), for the temperature range 1073-1673 K (covering typical operating temperatures and off-normal scenarios) are established. The following Arrhenius relationship for the parabolic constant describing ZrC growth is derived: Kp (in μm2/s) = 609.35 exp(-1.505 × 105/RT)). Overall, the ZrC growth is sluggish below 1473 K which is within the operational temperature range of SMRs. In all cases the ZrC that forms from solid state reaction is hypo-stoichiometric, as confirmed through XRD. The hardness and elastic modulus of carburized Zry-4 are also examined and it is shown that despite the formation of a ZrC layer, C ingress in the Zry-4 bulk does not impact the mechanical response after carburization at 1073 K and 1473 K for 96 h.

Study of Cost and Construction Speed of Cladding Wall for Lightweight Steel Frame (LSF)

The strategic issue faced by the Ministry of Public Works and Housing, Republic of Indonesia (PUPR) is the large housing backlog, especially in the urban areas. Low-income communities earning less than 2 USD/day are found as the most vulnerable to lack of access to affordable housing. This experiment aims to find an alternative solution on building construction material in accordance with the Ministry of Public Housing regulation No. 11 of 2011 about affordable housing guidelines. The experiment was carried out on an LSF to compare four different wall cladding materials. The building area was 36 m2 and the total wall cladding area was 95 m2. The wall cladding materials used were metal sheet, lightweight concrete brick, gypsum reinforced cement (GRC) board, and unplasticized polyvinyl chloride (uPVC) fiber. The experiment collected data on purchases of materials to develop the S-curve and measure construction progress. Then, the work unit price analysis (WUPA) approach was carried out to simulate the labor coefficient of construction speed and its comparison to the material costs of the four wall cladding materials. The experiment on this 36 m2 house found that metal sheet is the most efficient material, which took 22.7 h to cover a 95 m2 wall. Later, it was followed by uPVC fiber with 46.6 h, GRC board with 59.7 h, and finally lightweight con-bricks with 85.7 h. Apparently, the metal sheet not only presented the most efficient construction time, but also provided the lowest construction cost with 115.960 IDR/m2 (8.24 USD/m2). It was followed by uPVC fiber at 133.37 IDR/m2 (9.48 USD/m2); GRC board at 146.91 IDR/m2 (10.44 USD/m2) and finally lightweight con-bricks at 156.88 IDR/m2 (11.15 USD/m2). Through WUPA, this study also found that efficient workmanship (construction speed) of the labor greatly affects construction costs.

COLLISION CASCADE AND PRIMARY RADIATION DAMAGE IN SILICON CARBIDE: A MOLECULAR DYNAMICS STUDY

Silicon carbide (SiC) is a competitive candidate material to be used in several advanced and Generation-IV nuclear reactor designs as neutron moderator, fuel coating, cladding, or core structural material. Many studies have been performed to investigate the durability of SiC in severe environment in nuclear reactor. However, the nature and behavior of defect induced by neutron irradiation are still not fully understood. This paper is aimed to study collision cascade and primary radiation damage in SiC using molecular dynamics simulation. The potential being used was a hybrid Tersoff potential modified with Ziegler-Biersack-Littmark (ZBL) screening function. The collision cascade was let evolved for 10 ps from a Si or C primary knocked atom (PKA) located initially at the top center of a system containing 960000 atoms. The simulation was carried out at room temperature as well as at several advanced fission reactor-relevant temperatures. It was obtained that the number of C point defects were larger than the number of Si point defects. The number of stable point defect was found to be temperature-dependent. It was also obtained that the recovery of point defects was larger at high temperature (>800°C).

Investigations on Additively Manufactured Stainless Bearings

Additive manufacturing with multi-material design offers great possibilities for lightweight and function-integrated components. A process chain was developed in which hybrid steel–steel-components with high fatigue strength were produced. For this, a material combination of stainless powder material Rockit® (0.52 wt.% C, 0.9% Si, 14% Cr, 0.4% Mo, 1.8% Ni, 1.2% V, bal. Fe) cladded onto ASTM A572 mild steel by plasma arc powder deposition welding was investigated. Extensive material characterization has shown that defect-free claddings can be produced by carefully adjusting the welding process. With a tailored heat treatment strategy and machining of the semi-finished products, bearing washers for a thrust cylindrical roller bearing were produced. These washers showed a longer fatigue life than previously produced bearing washers with AISI 52100 bearing steel as cladding. It was also remarkable that the service life with the Rockit® cladding material was longer than that of conventional monolithic AISI 52100 washers. This was reached through a favourable microstructure with finely distributed vanadium and chromium carbides in a martensitic matrix as well as the presence of compressive residual stresses, which are largely retained even after testing. The potential for further enhancement of the cladding performance through Tailored Forming was investigated in compression and forging tests and was found to be limited due to low forming capacity of the material.

Uncertainty quantification in elastic constants of SiCf/SiCm tubular composites using global sensitivity analysis

Silicon carbide fiber and silicon carbide matrix (SiCf/SiCm) tubes produced through the chemical vapor infiltration process have become a candidate cladding material in nuclear applications. The performance of this composite is influenced by many variables such as braiding angle, porosity, material properties, etc., which vary over a range of values due to the inherent fluctuations in the manufacturing process. In this study, the variability in elastic constants of SiCf/SiCm composite has been quantified through multiscale finite element (FE) simulations, variable screening, and high-fidelity surrogate modeling. The key variables dominantly affecting the elastic constants of SiCf/SiCm tubes were identified using global sensitivity analysis. A surrogate to the high-fidelity FE-based model was used in Monte Carlo simulations to generate a hundred thousand samples from which the uncertainty in elastic constants was assessed. It turned out that the coefficient of variation was less than 10%.

Application Research of Laser Cladding Remanufacturing Technology to Repair Worn Mold

In recent years, with the development of laser technology and the transformation and upgrading of domestic manufacturing industry, the application of laser cladding remanufacturing technology is increasing. Mold as a common equipment of industrial production, its service life directly affects the production cost and efficiency of the enterprise.Wear is a common form of mold failure. In order to restore the performance of the mold and prolong the service life of the mold, The laser cladding remanufacturing technology to repair worn mold is studied in this paper. Firstly, the laser cladding remanufacturing is outlined, and the main technological process of the mold laser cladding remanufacturing is introduced. Then, taking 45 mold steel as an example, based on the analysis of the die material and weldability, the laser cladding material is selected reasonably, the mold is remanufactured by the experimental method, and the metallographic microscope analysis, hardness test and wear test are carried out.The research results show that the average hardness of the worn mold surface is about 55.5HRC after being remanufactured by laser cladding, and the wear resistance is doubled, and a good application effect has been achieved. Therefore, the laser cladding remanufacturing technology has a broad application prospect in repairing worn mold.

Trends in Residential Building Materials in the State of Victoria

As the population in Victoria continues to grow, there has been a corresponding increase in building approvals across the State. Houses characterised as low-rise residential buildings often take the largest share of these approvals, with incessant residential building activities being driven by record low interest rates. Low-rise residential buildings comprise various building forms that use a number of specified construction materials to construct the building envelope and other structural and non-structural elements. As materials used for constructing residential building envelopes continue to evolve, these materials must be fit for purpose, and satisfy design criteria and performance requirements, while being aesthetically pleasing. This research analyses the trend in construction materials used in building envelopes of low-rise residential buildings using data from building permits issued between 1996 to 2019. The trend analysis shows that traditional double brick wall systems and suspended timber floors have reduced in popularity for houses built in the 21st century. The analysis also shows that brick veneer wall cladding systems built over slab-on-ground footings is the dominant construction form while the roof cladding material is influenced by geographical location. Insights from the data analysis indicate very little innovation has emerged in materials for residential building envelopes despite its crucial role in providing thermal comfort for inhabitants. Results from this research will serve as a basis to provide quantitative assessment of the trend in materials resource; provide insights about the impact of new building envelope products on existing industries; and perspectives on materials for future building envelopes.

High-temperature oxidation of zirconium alloys with magnetron sputtered chromium coatings

Loss-of-coolant accidents (LOCAs) often lead to dire consequences. That’s why the global community are actively engaged in research aimed at creating accident tolerant fuels. One of the areas of such research is preserving zirconium alloys as the material for fuel-element claddings by creating corrosion-resistant coatings that would be in contact with the coolant. Chromium could be a promising material to be used in such protective coatings as chromium oxide (Cr2O3) serves as an effective barrier for oxygen both in normal operation and in case of LOCA. Chromium coating hinders oxygen diffusion into the metal substrate and thus prevents embrittlement and failure of the fuel-element cladding. This paper describes the results of research studies that have been carried out in recent years and that look at the resistance of magnetron sputtered chromium coatings to high-temperature oxidation in water vapour up to 1,500 oC. The paper demonstrates advantages and drawbacks of chromium coatings in hightemperature oxidation conditions. The focus is on understanding how regimes of magnetron sputtering influence the resistance of chromium coatings to high-temperature oxidation and how the structure and phase state of chromium coatings are related to their properties. The authors describe the optimal regimes of magnetron sputtering for obtaining dense coatings and examine the effect of the substrate temperature and the bias voltage on the structure and density of resulting coatings. High Power Impulse Magnetron Sputtering (HiPIMS) serves as an effective technique that helps enhance the density of coatings. The conclusion drawn is that in order to broaden the temperature range in which chromium coatings can effectively protect zirconium alloys from failure up to 1500 oC, there should be a diffusion barrier between the surface of the fuel-element cladding and the chromium coating. The authors would like to thank B. A. Kalin, supervisor of this project, who had passed away before this publication was made. The staff of the Laboratory of Ion-Plasma and Ion-Beam Machining of Materials, a part of Department No. 9 at the National Research Nuclear University MEPhI, devote this paper to his memory.

Microstructure and tensile properties of nano-sized ZrC particle strengthened RAFM steels

Reduced activation ferritic/martensitic (RAFM) steels containing ZrC nano particles (ZrC-RAFM steels) were prepared by a combination of spark plasma sintering (SPS) and hot-rolling of the mechanical alloyed powders. Moreover, the microstructure and tensile properties of the prepared ZrC-RAFM steels were investigated. The results show that the ZrC nano particles are uniformly dispersed in the RAFM steels, resulting in a significant decrease in grain size and the enhanced tensile properties of the steels. With the increase of ZrC content, the hardness and tensile strength of the steels are improved, and the mechanism of the improved properties is analyzed and discussed. The tensile strength of the 0.75ZrC- RAFM steel is 2069 MPa, which is 19.6% higher than that (1730 MPa) of the RAFM steel without ZrC. The conclusions provide researchers with the roles of ZrC-nanoparticle in micromorphology and tensile properties of the RAFM steel as potential cladding materials for fast reactors.

Chromium-Coated Zirconium Cladding Neutronics Impact for APR-1400 Reactor Core

The accident-tolerant fuel concept involves replacing the conventional cladding system (zirconium) with a new material or coating that has specific thermomechanical properties. The aim of this study is to evaluate the neutronics performance of a chromium coating concept and design solutions. A Zircaloy–uranium fuel system (Zr–U) is currently used as a standard fuel system in pressurized water reactors around the world. This investigation presents the benefits of utilizing an alternative cladding material such as chromium coating and the effects on the thermal neutron parameters of the way in which the chromium coating is introduced in the reactor fuel. Among these significant benefits is an increase in the reactor fuel’s thermal conductivity, which improves reactor safety. Two types of fuel-cladding systems were investigated: Zircaloy–uranium (Zr–U) and Zircaloy–chromium (Zr–Cr–U) coating fuel systems. Neutronics analysis evaluations were performed for the selected fuel assemblies and a two-dimensional full core based on an APR-1400 reactor design. Neutronics analyses were performed for the application of the new fuel-cladding material systems using the reactor-physics Monte Carlo code Serpent 2.31.

Experimental and theoretical investigation on the effect of surface porosity on the nucleate flow boiling heat transfer

The surface porosity of accident tolerant fuel cladding materials is different from the fuel material inservice at nuclear power plant, which leads to differences in the heat transfer characteristics. An experiment was conducted to investigate the effect of surface porosity on the nucleate flow boiling heat transfer. The results showed that bubbles on the SiC surface appear to be more uniform and remain isolated longer after bubble generation, and the average diameter of bubbles on the SiC surface tends to be smaller than that on the FeCrAl alloy surface. The nucleation site density is power-law dependent on porosity and superheat, and negative power-law dependent on critical cavity diameter and coolant subcooling. For the same degree of temperature increase on both surfaces, the number of nucleation sites on the surface with larger porosity increases much more than that on the surface with lower porosity, while the coolant subcooling degree inhibits the bubble nucleation and shrinks the bubble detachment diameter accordingly. A new correlation was proposed based on dimensional analysis, and the predictions were compared with the present experimental data and the other research data, with an 86% confidence interval of ± 50% for the consolidated datasets. Furthermore, the side-by-side comparison of the performance on these correlations showed that the present correlation, which includes surface porosity and roughness factors, significantly reduces the prediction error compared to the previous correlations.

Highly-doped YAG:Sm3+ transparent ceramics: Effect of Sm3+ ions concentration

YAG:Sm3+ (3–15 at.%) transparent ceramics, a promising cladding material for suppressors of parasitic oscillations at 1064 nm of YAG:Nd3+ lasers, have been prepared by solid-state reactive sintering at 1725 °C. The effect of samarium ions concentration on the microstructure and optical properties of YAG:Sm3+ sintered ceramics was studied for the first time. The solubility limit of samarium ions in the garnet matrix was found to lie within the range of 9–11 at.%. The spectroscopic characterization of YAG:Sm3+ (3–15 at.%) ceramic samples showed that the absorption coefficients corresponding to Sm3+ ions transitions increased linearly with increasing Sm3+ doping. Also, the increase in the concentration of Sm3+ ions contributes to the increase in the intensities of the satellites, leading to the broadening of the main spectral lines and implicitly to the increase of the absorption coefficient around 1064 nm. It was shown that YAG:Sm3+ ceramics doped with 9 at.% Sm3+ ions possess optical losses of 0.07 cm−1 at 808 nm and an optical absorption coefficient of 4.45 cm−1 at 1064 nm. The concentration dependence of the 4G5/2 level decay confirmed that the luminescence extinction is due to the energy transfer between the Sm3+ ions through cross-relaxation processes. All these results show that highly-doped YAG:Sm3+ (9 at.%) ceramics could be the best candidate for parasitic oscillation suppression in high-power YAG:Nd3+ lasers at 1064 nm.

Effect of aluminum on the FeCr(Al) alloy oxidation resistance in steam environment at low temperature (400 °C) and high temperature (1200 °C)

The effect of aluminum in the FeCr(Al) alloys on the corrosion behavior was studied at two temperatures (400 °C and 1200 °C). For the Fe-21Cr alloy, Cr2O3 layer was formed upon exposure to both temperatures. The addition of Al altered the corrosion mechanism of the alloy. At 1200 °C, a thin α-Al2O3 is formed on the Fe-21Cr-5.5Al alloy. Whereas, at low temperature, a continuous Cr2O3 is formed at the top with an internal Al2O3 layer. These results show that FeCrAl alloys hold promise as Fuel Cladding Materials with Al playing a crucial role under operational as well as accident-like conditions.

Optical Properties of a Tapered Optical Fiber Coated with Alkanes Doped with Fe3O4 Nanoparticles

The presented research shows the possibilities of creating in-line magnetic sensors based on the detection of changes of light propagation parameters, especially polarization, obtained by mixing Fe3O4 nanoparticles with hexadecane (higher alkane) surrounding a biconical optical fiber taper. The fiber optic taper allows to directly influence light parameters inside the taper without the necessity to lead the beam out of the structure. The mixture of hexadecane and Fe3O4 nanoparticles forms a special cladding surrounding a fiber taper which can be controlled by external factors such as the magnetic field. Described studies show changes of transmission (power, loss) and polarization properties like azimuth, and ellipticity, depending on the location of the mixture on sections of tapered optical fiber. The taper was made of a standard single-mode telecommunication fiber, stretched out to a length of 20.0 ± 0.5 mm and the diameter of the tapers is around 15.0 ± 0.3 μm, with the loss lower than 0.5 dB @ 1550 nm. Such a taper causes the beam to leak out of the waist structure and allows the addition of the external beam-controlling cladding material. The presented research can be used to build polarization switches or optical sensor. The results show that it can be a new way to control the propagation parameters of a light beam using tapered optical fiber and magnetic mixture.

Mathematical modelling to predict springback in bimetallic material including material anisotropy during bending

ABSTRACT The use of cladded material in industries has raised with an increase in the need for materials having improved strength, corrosion resistance and a high strength-to-weight ratio. This property gives the component increased component life and other desirable properties at low weight. Springback prediction is one of the crucial criteria for layered material. One parameter affecting the springback of the material is its anisotropy. This property of material should be taken into account to have better springback prediction. An attempt is made to incorporate the effect of anisotropy in the analytical model reported in the literature for a better prediction of the springback of the bimetallic plate. The results of the model are compared with the reported isotropic model and experimental results. It was found that consideration of anisotropy improved the result by 0.3% for a smaller bend radius. The comparison between isotropic and anisotropic conditions showed that the difference in the result is much greater at the higher bend radius. The percentage difference in unloaded radius raises to around 50% at the bend radius of 600 mm on consideration of the anisotropy for the bimetallic plate of 1.56 mm thickness. Thus, consideration of anisotropy is important at the larger bend radius.

SIMULATION OF HEAT GENERATION IN FRICTION SURFACE CLADDING (FSC) OF MULTILAYER AA2024

Friction surface cladding (FSC) is a solid-state cladding process that produces a thin metal layer on the substrate. It can be utilised at the surface to change the mechanical and corrosive properties of structural materials. There is a lack of retaining between the clad material and the substrate, resulting in loss of retaining between the clad material and the substrate. In this project, to estimate the heat generation during friction surface cladding (FSC) process for multilayer AA2024 using comsol multiphysics 5.5. The process parameter with different layer thickness has been investigated. Clad layer thickness 0.4mm -1.6mm (0.4mm each layer) with constant rotation speed 600rpm and translation speed 30mm/min was tested in this simulation to detect heat distribution. From the simulation result, the temperature increases significantly when cladding process started. With the thickness layer 0.4mm, the simulation shows the highest temperature which is same as the experimental result. For the conclusion, the clad layer thickness can affect the heat generation during friction surface cladding. As a result, the rate of heat generation is inversely proportional to the thickness of the clad layer. The thicker the clad layer, the lower the rate of heat distribution.