Ultra-high-temperature testing of sintered ZrB2-based ceramic composites in atmospheric re-entry environment

Mungiguerra, Stefano; Martino, Giuseppe D. Di; Cecere, Anselmo; Savino, Raffaele; Zoli, Luca; Silvestroni, L.; Sciti, Diletta

doi:10.1016/j.ijheatmasstransfer.2020.119910

Cited by 41 publications

(18 citation statements)

References 45 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…We primarily investigated pyrolysis at temperatures of 1500, 2500 and 3500 K. While some of these temperatures are higher than the 2000 K typically experienced during atmospheric re-entry [44], higher temperatures increase the rate of decomposition sufficiently to make carbonised structures accessible on reasonable timeframes (\ 4000 core hours). We also recorded trajectories and bonding information to examine how heating rate and temperature impacted the progression of the pyrolysis process and the final structure of the char.…”

Section: Methodsmentioning

confidence: 99%

Simulating the complete pyrolysis and charring process of phenol–formaldehyde resins using reactive molecular dynamics

et al. 2022

View full text Add to dashboard Cite

We examine the mechanism of pyrolysis and charring of large (> 10,000 atom) phenol–formaldehyde resin structures produced using pseudo-reaction curing techniques with formaldehyde/phenol ratios of 1.0, 1.5 and 2.0. We utilise Reactive Molecular Dynamics (RMD) with a hydrocarbon oxidation parameter set to simulate the high-temperature thermal decomposition of these resins at 1500, 2500 and 3500 K. Our results demonstrate that the periodic removal of volatile pyrolysis gasses from the simulation box allows us to achieve near complete carbonisation after only 2 ns of simulation time. The RMD simulations show that ring openings play a significantly larger role in thermal decomposition than has previously been reported. We also identify the major phases of phenolic pyrolysis and elucidate some of the possible mechanisms of fragment formation and graphitisation from the RMD trajectories and compute the thermal and mechanical properties of the final pyrolysed structures. Graphical abstract

show abstract

Section: Methodsmentioning

confidence: 99%

Simulating the complete pyrolysis and charring process of phenol–formaldehyde resins using reactive molecular dynamics

et al. 2022

View full text Add to dashboard Cite

show abstract

“…However, there is an inherent drawback in the fabrication of ZrB 2 -based UHTC components. Due to their strong covalent bonding and low self-diffusion, in most conditions, UHTCs need to be hot-pressed at temperatures above 1800 • C, depending on the sintering parameters (pressure, soaking time, heating rate) and/or sintering additives [21][22][23][24][25][26][27][28][29][30]. However, the hot-pressing technique typically produces disks or cylindrical objects, limiting to relatively simple geometrical and moderate sizes.…”

Section: Introductionmentioning

confidence: 99%

Colloidal Processing of Complex-Shaped ZrB2-Based Ultra-High-Temperature Ceramics: Progress and Prospects

2022

View full text Add to dashboard Cite

Ultra-high-temperature ceramics (UHTCs), such as ZrB2-based ceramics, are the most promising candidates for ultra-high-temperature applications. Due to their strong covalent bonding and low self-diffusion, ZrB2-based UHTCs are always hot-pressed at temperatures above 1800 °C. However, the hot-pressing technique typically produces disks or cylindrical objects limiting to relatively simple geometrical and moderate sizes. Fabrication of complex-shaped ZrB2-based UHTC components requires colloidal techniques. This study reviews the suspension dispersion and colloidal processing of ZrB2-based UHTCs. The most important issues during the colloidal processing of ZrB2-based UHTCs are summarized, and an evaluation of colloidal processing methods of the ZrB2-based UHTCs is provided. Gel-casting, a net or near-net colloidal processing technique, is believed to exhibit a great potential for the large-scale industrialization of ZrB2-based UHTCs. In addition, additive manufacturing, also known as 3D printing, which has been drawing great attention recently, has a great potential in the manufacturing of ZrB2-based UHTC components in the future.

show abstract

“…Reactions between transition metals, Mo in our case, and the fibers jeopardize their benefit on the mechanical properties of the ZrB 2 composite already during the sintering process. Although a ZrSi 2 addition also promotes full densification of ZrB 2 already at temperatures around 1500°C, due to the formation of low melting phases, which is vital to keep the integrity of the SiC fibers, the addition of ZrSi 2 does only offer a very low oxidation resistance as compared to MoSi 2 8,25,26 …”

Section: Introductionmentioning

confidence: 99%

“…Although a ZrSi 2 addition also promotes full densification of ZrB 2 already at temperatures around 1500 • C, due to the formation of low melting phases, which is vital to keep the integrity of the SiC fibers, the addition of ZrSi 2 does only offer a very low oxidation resistance as compared to MoSi 2 . 8,25,26 In view of the unfavorable performance of the MoSi 2 addition in combination with SiC fibers, a tailored phase F I G U R E 1 Schematic of the functionally graded sample geometry with (i) the oxidation resistant ZrB 2 -MoSi 2 top layer, (ii) a Mo-impermeable buffer layer based on ZrB 2 with either Si 3 N 4 , SiCN, or SiHfBCN as buffer-layer additive and (iii) a SiC short fiber reinforced ZrB 2 -ZrSi 2 bulk. Please note that this schematic is not true to scale.…”

Section: Introductionmentioning

confidence: 99%

Prevention of SiC‐fiber decomposition via integration of a buffer layer in ZrB₂‐based ultra‐high temperature ceramics

2022

Self Cite

View full text Add to dashboard Cite

A ZrB2‐based ceramic, containing short Hi‐Nicalon SiC fibers, was fabricated with a Mo‐impermeable buffer layer sandwiched between bulk and the outermost oxidation resistant ZrB2–MoSi2 layer, in order to prevent inward Mo diffusion and associated fiber degradation reactions. This additional layer consisted of ZrB2 doped with either Si3N4 or with the polymer‐derived ceramics (PDCs) SiCN and SiHfBCN. Scanning electron microscopy imaging and elemental mapping via energy‐dispersive X‐ray spectroscopy showed that this tailored sample geometry provides an effective diffusion barrier to prevent the SiC fibers from deterioration due to reactions with Mo or Mo‐compounds. In contrast, the structure of the SiC fibers in a reference sample without buffer layer is strongly degraded by MoSi2 diffusion into the fiber core. The comparison of the three buffer‐layer systems showed a moderate alteration of the fiber structure in the case of Si3N4 addition, whereas in the PDC‐doped samples hardly any structural change within the fibers was observed. A stepwise reaction mechanism is deduced, based on the continuous progression of a reaction zone that propagates toward the ZrB2–MoSi2 top layer. The progression of such a reaction zone as a consequence of the different eutectic melts forming in the different layers, that is, first in the SiC‐fiber‐containing bulk, then in the buffer layer itself, and finally in the top layer at high temperature, allows for an effective separation of the ZrB2–MoSi2 top layer from the SiC fibers. Subsequent oxidation at 1500°C and 1650°C for 15 min did not affect the efficiency of all three buffer layers, since no structural changes regarding buffer layer and fibers were observed, as compared to the non‐oxidized samples.

show abstract

Ultra-high-temperature testing of sintered ZrB2-based ceramic composites in atmospheric re-entry environment

Cited by 41 publications

References 45 publications

Simulating the complete pyrolysis and charring process of phenol–formaldehyde resins using reactive molecular dynamics

Simulating the complete pyrolysis and charring process of phenol–formaldehyde resins using reactive molecular dynamics

Colloidal Processing of Complex-Shaped ZrB2-Based Ultra-High-Temperature Ceramics: Progress and Prospects

Prevention of SiC‐fiber decomposition via integration of a buffer layer in ZrB₂‐based ultra‐high temperature ceramics

Contact Info

Product

Resources

About

Ultra-high-temperature testing of sintered ZrB2-based ceramic composites in atmospheric re-entry environment

Cited by 41 publications

References 45 publications

Simulating the complete pyrolysis and charring process of phenol–formaldehyde resins using reactive molecular dynamics

Simulating the complete pyrolysis and charring process of phenol–formaldehyde resins using reactive molecular dynamics

Colloidal Processing of Complex-Shaped ZrB2-Based Ultra-High-Temperature Ceramics: Progress and Prospects

Prevention of SiC‐fiber decomposition via integration of a buffer layer in ZrB2‐based ultra‐high temperature ceramics

Contact Info

Product

Resources

About

Prevention of SiC‐fiber decomposition via integration of a buffer layer in ZrB₂‐based ultra‐high temperature ceramics