About
285
Publications
38,477
Reads
How we measure 'reads'
A 'read' is counted each time someone views a publication summary (such as the title, abstract, and list of authors), clicks on a figure, or views or downloads the full-text. Learn more
9,884
Citations
Introduction
Skills and Expertise
Current institution
Publications
Publications (285)
For the first time, ultra-high temperature ceramic matrix composite bars were tested inside an arc-jet facility to investigate the impact of oxidation damage on strength retention. The composite bars, which were based on a ZrB2/SiC matrix reinforced with 45 vol% carbon fibers, were produced by slurry impregnation and sintering. The first batch was...
Particle-induced x-ray emission (PIXE) is a well-established ion-beam analysis technique, enabling quantitative measurement of the elemental composition of a sample surface under an ambient atmosphere with an external beam, which significantly simplifies the measurements, and is strictly necessary for those samples that cannot sustain a vacuum envi...
Carbon fibre-reinforced ultra-high temperature ceramics (UHTCs) are considered a class of promising materials for several applications, the most appealing ones being in the aerospace sector. Reinforcement is necessary to overcome the brittleness and low thermal shock resistance of ceramics and is often provided through the addition of carbon fibres...
TiB2 is a promising material for several fields including impact-resistant armor, wear-resistant coatings, cutting tools and crucibles given its physical, mechanical and chemical properties, especially due to the combination of high hardness and exceptional wear resistance. It is however very difficult to sinter below 2000 °C, even under mechanical...
Ultra-high-temperature ceramic matrix composites (UHTCMCs) based on a ZrB2/SiC matrix have been investigated for the fabrication of reusable nozzles for propulsion. Three de Laval nozzle prototypes, obtained by sintering with either hot pressing (HP) or spark plasma sintering (SPS), were tested 2–3 times in a hybrid rocket motor for proving reusabi...
Tantalum boride is an ultra-refractory and ultra-hard ceramic known so far for its favorable high-temperature thermo-mechanical properties and also characterized by a low spectral emittance, making it interesting for novel high-temperature solar absorbers for Concentrating Solar Power. In this work, we investigated two types of TaB2 sintered produc...
📝 For 50 days only, the paper can be downloaded here: https://authors.elsevier.com/a/1gtxT3PCJlPlYD
A new additive technique for manufacturing of short fibre-reinforced ultra-refractory ceramics is presented. This technique allows the fabrication of solvent-free, thin (~100 µm), flexible, and easy-to-handle sheets suitable for fabricating homogeneous or layered structures. A large range of compositions, in terms of matrix and fibre volumetric con...
Surfaces of commercial molybdenum (Mo) plates have been textured by fs-laser treatments with the aim to form low-cost and efficient solar absorbers and substrates for thermionic cathodes in Concentrated Solar Power conversion devices. Morphological (SEM and AFM), optical (spectrophotometry), and structural (Raman spectroscopy) properties of the sam...
The development process of new Ultra High-Temperature Ceramic Matrix Composites (UHTCMC) for use in severe environments typical of space applications, such as thermal protection or rocket components, still lacks useful data for what concerns the properties influencing the structural behavior under the different load conditions. In particular, the f...
To maximize the toughening contributions due to fiber bridging and residual stresses upon layering, ultra-high temperature ceramics containing variable amounts of short carbon fiber in functionally graded stacking sequences were designed and characterized. Stress fields evaluated by finite element model on (AB)nA and more complex asymmetric archite...
Cf/ZrB2–SiC composites were produced by water-based slurry impregnation followed by six cycles of polymer infiltration and pyrolysis at 1000 °C. Despite the mild temperature of pyrolysis, the flexural strength of this composite showed values in excess of 500 MPa even at elevated temperature, up to 1400 °C. The abrupt decay of strength at 1500 °C st...
B4C-TiB2 composites with classical 75/25 vol ratio were sintered by pressureless sintering with and without gas pressure application in the final stage of densification, using a novel prototypal furnace. A small fraction of WC was introduced through high energy milling of the starting powders with WC-Co spheres. High energy milling facilitated the...
The reusability of CMCs with inherently high-temperature capabilities and ablation resistance goes through understanding of the effects of residual thermal stresses (RTS) caused by thermal expansion mismatch between fibre and matrix. In this work, the RTS of ultra-high temperature ZrB2–SiC based ceramic reinforced with carbon fibres was dependent o...
A significant improvement of the mechanical performance was observed following the introduction of rare earth oxides in ZrB2-based ultra-high temperature ceramic matrix composites (UHTCMCs), resulting in the formation of ternary boro-carbides of general formula REB2C2, belonging to a new class of layered compounds akin to MAX phases. These layered...
Uncoated PAN-based carbon fibre reinforced ultra-high temperature ceramic matrix composites via aqueous ZrB2 powder-based slurry impregnation coupled with mild polymer infiltration and pyrolysis, using allylhydrido polycarbosilane as source of amorphous SiC(O) were manufactured. To demonstrate the versatility of the process to realize tailored mate...
A partially porous SiC ceramic, reinforced with 30 vol% short carbon fibers, was hot pressed and characterized as potential ISOL target for nuclear applications. Powder milling and hot pressing were effective for the realization of a ceramic with about 40% interconnected porosity in the 0.6-0.8 µm size range. A fiber-free porous SiC material was al...
Systematic dry sliding wear tests with monolithic ZrB2 and Al2O3 pins coupled to ZrB2, ZrB2-20vol% SiC and Al2O3 discs were carried out in a disc-on-pin configuration. The steady state friction of ZrB2 self-mated or cross coupled with Al2O3 was about 1.1. Self-mated monolithic ZrB2 discs worn about three orders of magnitude more than self-mated Al2...
Ultra-high temperature ceramic matrix composites (UHTCMCs) are a new class of composites which combine boride phases with carbon fibres to achieve new structural and functional properties and were originally designed for aerospace applications. For the first time, this work investigates the optical response of UHTCMCs in view of their possible appl...
White conventional zirconium oxide was mixed to black or rust coloring second phase additives to increase the absorptance and thermal emittance with the aim of exploring novel oxide-based ceramics for energy exploitation and saving, like solar absorbers or even industrial refractory kiln walls. The variation of the optical properties of the colored...
Continuous carbon fibre ceramic matrix composites capable of tolerating multiple thermal-shock cycles and resisting ablation are needed for aerospace and hypersonic systems. Carbon fibre around 50 vol% and ultra-refractory matrices are fundamental parameters. The influence of rare earth (RE) oxides on the microstructure and mechanical properties of...
Ultra-High Temperature Ceramic Matrix Composites (UHTCMCs) are the next generation composites developed for application in the harsh environment of aerospace. Qualification of these materials requires the manufacturing of demonstrators for testing in relevant environments, which in turn, requires to scale them up. This paper illustrates the systema...
Magnesium aluminate and other alumina-based spinels attract attention due to their high hardness, high mechanical strength, and low dielectric constant. MgAl2O4 was produced by a solid-state reaction between MgO and α-Al2O3 powders. Mechanical activation for 30 min in a planetary ball mill was used to increase the reactivity of powders. Yttrium oxi...
Carbon fibre reinforced ultra-high temperature ceramic (UHTC) matrix composites were fabricated coupling water-based powder slurry infiltration, Polymer Infiltration and Pyrolysis (PIP) and Hot Pressing techniques (HP). This study aims to identify the best sequence of consolidation techniques to better integrate the carbon fibre cloths into an ultr...
Qualification and reusability campaigns were performed on ultra-high temperature ceramic matrix composites (UHTCMCs) made of a ZrB2-SiC matrix with short/long carbon fibre to assess their performance as thermal protection systems. Heat fluxes and stagnation pressures were set following those of reference re-entry missions. An interdisciplinary anal...
Oxy-acetylene torch testing was performed at a range of angles of attack on Cf/ZrB2-SiC-Y2O3 composites, from 10° to 90°. The ablation behaviour was studied in-situ with thermography, and the post-ablation morphologies investigated optically and with elemental analysis. Significantly lower surface temperatures were observed at oblique angles of att...
In the frame of Horizon 2020 European C3HARME research project, the manufacture of ZrB2-based CMCs was developed through different processes: slurry infiltration and sintering, radio frequency chemical vapour infiltration (RF-CVI) and reactive metal infiltration (RMI). To assess the high temperature stability, room temperature bending strength was...
The materials currently used in aerospace and aviation, such as C/C and C/SiC composites, possess excellent mechanical properties but are limited to a maximum operational temperature of 1600°C (C/SiC) and poorly oxidizing environments (C/C). For more demanding applications, new materials able to withstand extreme temperatures without recession are...
High-speed aviation brings many challenges, one being the materials used ensure the aircraft and rockets travelling at hypersonic speed arrive at their destination safely. Control surfaces and thermal protection systems for vehicles flying at Mach 5 or above must withstand extremely hot temperatures and intense mechanical vibrations at launch, duri...
The evolution of the multi-scale microstructure of a (Zr,Ta)B2 solid solution was studied as a function of time and temperature. The ceramics were produced by hot pressing mixtures of ZrB2 with 15 vol% TaSi2 followed by annealing at 2100 °C. Formation of a super-saturated solid solution led to the precipitation of TaC nano-needles within the micron...
The ultrahigh temperature ceramic-matrix composites (UHTCMCs) are the core class of innovative materials. One of the key-features that such a new class of materials should exhibit is self-repair of damage without any external intervention. In the present work, a set of ZrB2-SiC ceramics (SiC from 5 to 15 vol.%) was produced by hot-pressing: besides...
In this work, for the first time, we studied the temperature-dependent spectral emittance of highly refractory ceramics, e.g. silicon carbide (SiC) and two ultra-high temperature ceramics (tantalum diboride (TaB2), zirconium diboride (ZrB2)) to evaluate their potential for solar tower receivers applications. We measured the spectral normal emittanc...
Research efforts on Ceramic Matrix Composites (CMCs) are aimed to increase the operating temperature in oxidizing environments by adding Ultra-High Temperature Ceramic (UHTC) phases to the matrix. The structural performances of UHTC-enriched CMCs are generally investigated through bending test because it requires simple fixture and specimen geometr...
In the frame of Horizon 2020 European C³HARME research project, the manufacture of ZrB2-based CMCs was developed through different processes: slurry infiltration and sintering, radio frequency chemical vapour infiltration (RF-CVI) and reactive metal infiltration (RMI). To assess the high temperature stability, room temperature bending strength was...
The oxidation behaviour of Cf/ZrB2-SiC with different fibre architectures, manufactured by slurry impregnation, polymer infiltration and mild pyrolysis, was investigated. Short term oxidation tests in air were performed for 1 min and 5 min at 1500 °C and 1650 °C in a bottom loading furnace. Microstructure, oxide scale thickness and composition were...
Polycrystalline lanthanum hexaboride (LaB6) discs were sintered by hot pressing of commercial powders and successively polished, in order to investigate their thermionic emission capability. LaB6 samples presented values of work function in the range 2.55–2.61 eV. Discs with polished surface, independently from the composition and density, demonstr...
The influence of pressure on the oxidation resistance of C-ZrB2/SiC composites was studied. Materials were tested in air at 2000-2200 °C at 1-900 mbar. SEM analysis on the tested samples revealed the formation of an outer compact layer of ZrO2 and an intermediate layer of ZrO2-SiO2 as well as a porous interface layer of ZrO2. SiC increase was benef...
In this paper, for the first time, we report the manufacturing and characterization of large UHTCMCs discs, made of a ZrB2/SiC matrix reinforced with PyC-coated PAN-based carbon fibres. This work was the result of a long term collaboration between different institutions and shows how it is possible to scale-up the production process of UHTCMCs for...
Flash Spark Plasma Sintering (FSPS) was used to rapidly sinter pure titanium diboride (TiB2). A pre-sintered green body (Ø= 20 mm with relative density 60%) was discharged under a current of 2-2.5 kA flowing entirely across the sample. The samples were locally densified up to 98% of relative density in a very short time of 20 seconds. The rapid hea...
Direct absorption solar collector (DASC) are being considered of great interest in combination with colloidal systems consisting of nanoparticles dispersed in suitable liquids, also called nanofluids. Nanofluids are able to carry out, at the same time, the double function of volumetric solar absorbers and heat transfer media. In this work, novel ce...
The effects of SiC content on aero-thermal resistance capabilities of ZrB2-xSiC-5Y2O3 ceramics (x = 5,10,15,18.5 vol%) in atmospheric re-entry environment were investigated, exposing four hot-pressed button-like specimens to an arc-heated plasma wind tunnel supersonic flow (enthalpy up to 20 MJ/kg). As x increased, the maximum steady-state surface...
This work explores the fine microstructural features of B4C-TiB2 composites and suggests an overall microstructure evolution from powder processing to sintering. In addition, small-scale grain structures are correlated to local properties measured by nanoindentation, thus providing trends in mechanical behavior. Dense ceramics were typified by deve...
This paper presents the results of experimental tests for the characterization of Ultra-High-Temperature Ceramic Matrix Composite (UHTCMC) materials for near-zero erosion rocket nozzles. Two dedicated test set-ups were developed for preliminary screening of material candidates in a representative environment, characterized by relevant heat flux and...
The use of high power pulsed lasers is an effective tool for microstructuring material surfaces. It appears particularly useful when the material has some characteristics making difficult using other procedures (e.g. a high hardness). The present work reports on the femtosecond-laser treatment on tantalum diboride ultra-high temperature ceramics wi...
The microstructure and mechanical properties of carbon fibre reinforced ZrB2 composites produced by slurry infiltration and consolidated by reactive melt infiltration were investigated. Fibres were preliminary infiltrated with ZrB2/B slurries with varying ZrB2/B ratios. Then the composites were infiltrated with Zr2Cu melt at 1200 °C under vacuum. B...
White Zirconium oxide is featured by low absorptance, but addition of specific secondary coloring agents enables to increase its solar selectivity comparable to that of conventional materials used in solar power plants. Colored zirconia, generally used for decorative purposes, has thus the possibility to widen its application fields and to be a che...
An experimental campaign has been carried out to characterize a new class of Ultra-High-Temperature Ceramic Matrix Composites for near-zero ablation Thermal Protection Systems. Small-sized specimens, with ZrB2-based matrix and different carbon fiber architectures, were exposed to a simulated air supersonic flow generated by an arc-jet wind tunnel,...
A tungsten carbide ceramic containing 5 vol% silicon carbide was hot pressed to full density at 1820 °C. A small amount of transient liquid phase based on W-C-Si-O facilitated oxide removal in the reducing environment and favoured the development of a bimodal microstructure containing sub-micrometric grains with square or rod-like morphologies. The...
Surface characteristics and machining performances of micro-pockets manufactured by μEDM as a function of different process conditions are studied in this paper. The micro-pockets were obtained using different combinations of process parameters on different ultra-high temperature ceramics (UHTCs) with the same base matrix (ZrC) and different volume...
The influence of Y2O3 addition on the microstructure, thermo-mechanical properties and oxidation resistance of carbon fibre reinforced ZrB2/SiC composites was investigated. Y2O3 reacted with oxide impurities present on the surface of ZrB2 and SiC grains and formed a liquid phase, effectively lowering the sintering temperature and allowing to reach...
In this paper the microstructure and mechanical properties of two different Cf/ZrB2-SiC composites reinforced with continuous PyC coated PAN-derived fibres or uncoated pitch-derived fibres were compared.
Pitch-derived carbon fibres showed a lower degree of reaction with the matrix phase during sintering compared to PyC/PAN-derived fibres. The reaso...
The microstructure and mechanical properties of carbon fibre reinforced ZrB2 composites produced by slurry infiltration and consolidated by reactive melt infiltration were investigated. Fibres were preliminary infiltrated with ZrB2/B slurries with varying ZrB2/B ratios. Then the composites were infiltrated with Zr2Cu melt at 1200°C under vacuum. Bo...
Cf/ZrB2-SiC ultra-high temperature composites were manufactured via aqueous slurry impregnation coupled with polymer infiltration and pyrolysis, using a allylhydrido polycarbosilane precursor. For the first time we used ultra-high modulus pitch-based carbon fibres for the PIP process, investigating three different architectures, 0/0°, 0/90°, and 2D...
Concentrating solar power is one of the most promising solar energy exploitation technologies. Its efficiency improvement needs a significant increase of operating temperatures, from the current 500°C to 900°C. Alumina (Al2O3) ceramics are refractory materials characterized by a huge industrial interest, mature production techniques and low cost. I...
Ultra-High Temperature Ceramic Matrix Composites (UHTCMCs) are a new class of materials designed to merge the best features of ceramic matrix composites (CMCs), like damage tolerance, with those of ultra-high temperature ceramics (UHTCs), like ablation resistance. Applications that will benefit from these outperforming materials are found in aviati...
Strength retention of continuous carbon fiber-reinforced dense ZrB2-based ceramics (Cf/ZrB2) after thermal or indentation damage was evaluated. Thermal damage was in-situ induced and characterized by cyclic dilatometric analysis. Indentation damage was induced through Vickers indentation and then characterized by digital microscopy. The investigati...
For the first time we show that spark plasma sintering can efficiently replace hot pressing for the densification of UHTCMCs, in the present case ZrB2/SiC composites reinforced with continuous carbon fibres. To this purpose, the same materials were first produced by hot pressing as baseline samples and then by spark plasma sintering (SPS) to compar...
The residual carbon content of ultra-fine hafnium carbide (HfC) powder was controlled by the optimization of the synthesis process, and the effect of residual carbon on the densification of HfC powder was analyzed. The amount of residual carbon in the HfC powder could be reduced by the de-agglomeration of HfO2 powder before the carbo-thermal reduct...
High entropy metal diborides (HEBs) represent a radically new approach to extend the chemical composition window of ultra-high temperature ceramics (UHTCs). In this work, arc-melting was used to produce dense HEBs starting from UHTC powders. In order to understand the influence of each individual diboride within the quinary system (HfB2, ZrB2, TiB2...
A simple method to obtain a highly refractory HfB2-based ceramic nano-composite is presented. The boride was hot pressed with additions of SiC and WC particles and subsequently annealed at 2100 °C for 2 h. The annealing procedure was beneficial for high temperature strength, which increased by about 300 MPa in the 1500 °C–1800 °C temperature range...
A functionally graded composite based on ZrB2 and 0–50 vol% of short carbon fibres was prepared via a deliberately simple approach that involved creating a suitable stacking sequence of layers with different sintering agents and fibre contents. This led to an excellent combination of failure tolerance and oxidation resistance in a light material wi...
A super-strong ZrB2 ceramic containing WC and SiC was tested in a supersonic arc-jet wind tunnel by exposure to flows with two chemical compositions, simulated air or pure nitrogen, at temperatures of 2650 and 2800 K. Temperature jumps of 500–600 K were observed in both environments at constant flow conditions. SEM analyses revealed that oxygen in...
This study systematically correlates processing with quantitative microstructural information over an extended compositional range for ZrB2-MoSi2 ceramics, with MoSi2 contents ranging from 5 to 70 vol% and diboride starting particle sizes ranging from 3 to 12 μm. Fifteen different ceramics were hot pressed between 1750 and 1925 °C. Plastic deformat...
The mechanical behavior of ZrB2-MoSi2 ceramics made of ZrB2 powder with three different particle sizes and MoSi2 additions from 5 to 70 vol% was characterized up to 1500 °C. Microhardness (12–17 GPa), Young's modulus (450–540 GPa) and shear modulus (190–240 GPa) decreased with both increasing MoSi2 content and with decreasing ZrB2 grain size. Room...
Two samples of Ultra-High-Temperature Ceramic Matrix Composites, with carbon fibers in a ZrB2-SiC matrix, were exposed to supersonic dissociated air flow, simulating the atmospheric re-entry environment, in an arc-heated facility at specific total enthalpies up to 20 MJ/kg. Surface temperatures, exceeding 2400 K, were monitored by non-intrusive inf...
The influence of carbon fibre content on the mechanical behaviour of HfC/SiC composites was investigated up to 2100 °C for specimens containing 40 or 55 vol% fibres. Silicon carbide was added as a sintering aid during hot pressing. Increasing the fibre content made infiltration more difficult, which resulted in higher porosity in the specimen with...
Different configurations of continuous carbon fiber-reinforced ultrahigh temperature ceramics (UHTCs), by combining coatings and matrix, were produced via electrophoretic deposition (EPD) and slurry infiltration. The toughening of non-periodic fiber distribution induced by the EPD process was investigated through work of fracture analysis. The resu...
The excess carbon and oxygen contents of ZrC nano-powders was controlled, and the resultant effects on the densification of ZrC was analyzed. The particle size of the synthesized ZrC powder was about 200 nm and its oxygen content was 0.49 wt%. The good results can be attributed to the rapid heating and cooling rate, the beneficial effects of curren...
A new class of ZrB 2 composites reinforced with 40 vol% C short fibers and containing 5 vol% SiC in combination with 5 vol% MoSi 2 , HfSi 2 or WSi 2 successfully withstood extreme conditions in a oxyacetylene torch. Different responses to the torch testing were recorded depending on which secondary phase was present; this was primarily a result of...
MAX phases, and particularly Ti 3 SiC 2 , are interesting for high temperature applications. The addition of carbon fibers can be used to reduce the density and to modify the properties of the matrix. This work presents the densification and characterization of Ti 3 SiC 2 based composites with short carbon fibers using a fast and simple fabrication...
The microstructure and mechanical properties of hot-pressed alumina (Al2O3) matrix composites containing 20, 35, or 50 vol% of nickel aluminide (NiAl) were investigated. The mean Al2O3 grain size was found to decrease from approximately 2.0 μm (monolithic Al2O3) to 1.0 μm for the composite containing 50 vol% NiAl. Composite flexural strength values...
CSP (Concentrated Solar Power) plants technologies use the concentration of solar energy on a receiver to produce heat and then electricity by a thermodynamical process. A solar absorber material is used to convert the energy carried by light into heat. This type of material works at high temperatures (up to 1000 °C) under a highly concentrated sol...
The microstructure and elevated temperature mechanical properties of continuous carbon fibre reinforced ZrC and TaC composites were investigated. Silicon carbide was added to both compositions to aid sintering during hot pressing. Fibres were homogeneously distributed and no fibre degradation was observed at the interface with the ceramic matrix ev...
There is an increasing demand for advanced materials with enhanced temperature capability in highly corrosive environments, for instance enable space vehicles to resist several launches and re-entries. The EU-funded project C³HARME aims at combining the best features of CMCs and UHTCs to design, develop, manufacture and qualify a new class of Ultra...
Ultra-high temperature ceramic matrix composites (UHTCMCs) based on ZrB2-matrix reinforced with 45 vol% of unidirectional continuous carbon fibers are studied through the thermal mechanical hysteresis in order to investigate the thermal damage accumulation. The presented analysis allowed to extrapolate the Young's modulus of the matrix from thermal...
The thermionic‐thermoelectric solid‐state technology, characterized by solar‐to‐electric conversion efficiency feasibly >40%, is comprehensively proposed and discussed for conversion of concentrating solar power. For the first time, the related solar generator prototype is designed and fabricated by developing advanced materials functionalized for...
In the framework of the Horizon 2020 project C 3 HARME, an experimental campaign has been carried out to characterize a new class of Ultra-High-Temperature Ceramic Matrix Composites for near-zero ablation Aerospace Thermal Protection Systems. Small sized specimens, with ZrB2-based matrix and different carbon fiber architectures, were exposed to a s...
In the framework of the Horizon 2020 project C 3 HARME, an experimental campaign has been carried out to characterize a new class of Ultra-High-Temperature Ceramic Matrix Composites (UHTCMC) for near-zero erosion rocket nozzles. A novel test setup has been developed to the purpose of testing small-sized specimens, with ZrB2-based matrix and carbon...
An efficiency improvement of concentrating solar power systems relies on a significant increase of the operating temperatures, exceeding 600 °C. This goal can be achieved through the use of solar absorbers possessing high spectral selectivity and stability at such temperatures. Suitable alternatives to the largely used silicon carbide can be found...
