Thermochemical Erosion Research Articles

Enhanced mechanical property, high-temperature oxidation and ablation resistance of carbon fiber/phenolic composites reinforced by attapulgite

To meet the thermal protection and load-bearing requirements of ultra-high-speed vehicles, it is urgent to improve the ablation resistance, high-temperature oxidation resistance and mechanical properties of carbon fiber/ boron phenolic resin (CF/BPR) composites simultaneously. Herein, polyhedral oligomeric silsesquioxane-modified attapulgite (ASP) with abundant porous structure was successfully introduced into the CF/BPR (CF/ASPBPR). The co-effect of ceramization, high infrared emissivity, and low thermal conductivity endowed the CF/ASPBPR with desirable ablation resistance, where the linear ablation rate and mass ablation rate reduced to 0.038 mm/s and 0.035 g/s, respectively. Meanwhile, due to the high thermal stability and energy dissipation of ASP, the CF/ASPBPR also presented the interlaminar shear strength of 35.40 and 9.79 MPa before and after high-temperature treatment, which were 24 % and 63 % higher than that of CF/BPR, respectively. This study provides a promising pathway for preparing advanced thermal protection materials that can adapt to severe mechanical spalling and thermochemical erosion environments.

Inhibition of thermochemical erosion by different coatings attached to the barrel chamber at high temperature and supersonic environments

Inhibition of thermochemical erosion by different coatings attached to the barrel chamber at high temperature and supersonic environments

Transient numerical investigation on thermochemical erosion of C/C nozzles in hybrid rocket motors

Nozzle erosion is a vital important issue that impacts the performance of hybrid rocket motors. Serious nozzle erosion may significantly decrease the combustion chamber pressure and thrust, which increases the difficulty in designing flight control systems. This paper aims to reveal erosion mechanism systematically. In this paper, transient numerical simulations of thermochemical erosion in hybrid rocket motors are conducted, and combustion flow and thermochemical erosion are coupled calculated. The numerical computation of combustion flow is based on the chemical reactions of propellants and regression rate model, and that of thermochemical erosion is based on the surface reactions between oxidizing species and carbon. The movement of burning surface and nozzle inner surface is simulated through dynamic mesh method. The hybrid rocket motor adopts 90% hydrogen peroxide and hydroxyl-terminated polybutadiene. Distributions of flow field parameters and fuel regression rate are given. The spatial developing process of nozzle surface is presented, and it is found that the roughness of nozzle profile increases with time. The nozzle wall temperature and wall pressure decline with time. Erosion by different species is calculated. OH and H2O make a major contribution to the nozzle thermochemical erosion, while nozzle erosion contributed by CO2 and O2 are quite low. Time-varying characteristics of the erosion rate are unveiled. At the first 1.5 s, the total erosion rate remains almost constant, and then it reduces over time.

Mostly solidified hardground at the top of the crystal pile in the Bushveld magma chamber

Mafic layered intrusions show abundant evidence for the formation through the progressive inwards growth of a mushy solidification layer, with a central body of nearly crystal-free resident melt. The thickness and permeability of the mushy layer play a vital role in operation of several petrogenetic processes but remain poorly constrained in layered intrusions. To address this issue, we have re-examined the cumulate sequence in the Upper and Critical Zones of the Bushveld Complex. Although some observations (e.g., soft-sediment deformation) are indicative of cumulate rocks being mushy and having experienced interstitial melt percolation (e.g., metasomatic anorthosites), other field and textural evidence suggest the contrary. Some of the clearest evidence comes from sections through chromitite and magnetitite layers as well as through the Merensky Reef, layers that were deposited on the eroded rocks of the temporary chamber floor. Below the erosional surface, the layered rocks (1) were tilted and truncated without losing their internal coherence, (2) have knife-sharp contacts with the overlying rocks, (3) show minimal evidence of penetration by downward-percolating melt, (4) reveal sharp truncation of individual crystals, particularly beheading of pyroxene oikocrysts and intersecting of polysynthetic twinning in plagioclase, and (5) show resumed growth on the truncated crystals into the overlying rocks. These observations indicate that the cumulates of the inward-growing chamber floor were almost entirely solid at the time of the erosion and deposition of these layers. To reconcile these two sets of contrasting observations, we propose that only a few metres of the uppermost portion of the cumulate pile of the Upper and Critical Zones of Bushveld magma chamber were mushy, with other underlying rocks being almost totally solidified. The mushy layer tends to be thin and locally even non-existent (e.g., in magnetitite layers) due to high efficiency of primary adcumulus growth at the crystal-liquid interface of the temporary chamber floor. The solid chamber floor results from thermochemical erosion of the entire mushy layer by magmas replenishing the evolving chamber. The study implies that such petrogenetic processes as the hydrodynamic sorting of crystals and reactive porous flow may only operate within this very thin mushy portion of the cumulate pile and cannot therefore be responsible for any large-scale petrological features (e.g., platinum reefs, massive chromitites, stratiform anorthosite layers) of the Bushveld Complex.

Launching dynamics of terminal guidance projectile considering barrel erosion and mechanical wear

This paper simulates the launching dynamics of the Terminal-guidance projectile considering the barrel thermo-chemical erosion wear and mechanical wear. A thermochemical erosive material degradation model that considers the rise in friction temperature is first introduced. Moreover, the wear state of barrel rifling at different periods is calculated using the erosion wear model. A three-dimensional model of the worn barrel is established, and the coupled barrel– terminal-guidance projectile launch dynamics are simulated for different wear periods. Finally, the projectile's bore overload and attitude are analyzed to explore the effect of barrel wear on launch.

Experimental and numerical investigation on thermochemical erosion and mechanical erosion of carbon-based nozzles in hybrid rocket motors

In order to enhance energy characteristics of propellants in hybrid rocket motors, aluminum particles are added into the solid fuel. However, these particles may lead to nozzle mechanical erosion, which significantly affects the motor performance. This paper intends to study thermochemical and mechanical erosion mechanism of carbon-based nozzles in hybrid rocket motors with aluminum metallized fuel. A firing test is performed, and 95 % hydrogen peroxide and hydroxyl‑terminated polybutadiene based fuel with aluminum particles are utilized. Experimental results show that many metal particles are ejected from the nozzle, and aluminum oxide deposits heavily on the nozzle inner surface. A method of numerical calculation coupled with two-phase flow, combustion of aluminum metallized fuel, thermochemical ablation reactions, and mechanical erosion is established. The errors of combustion chamber pressure and throat erosion rate between numerical calculation and test results are 0.53 % and 7.76 %, respectively. Simulation results indicate that with the increase of aluminum content, nozzle wall pressure gradually increases, while the mass fraction of H2O, CO2, OH, and O declines. The nozzle wall temperature and thermochemical erosion rate raise first and then reduce as aluminum content increases. The mechanical erosion is mainly distributed in the convergent section, and it raises with the increase of aluminum content. When aluminum content is up to 38 %, the maximum mechanical and thermochemical erosion rates are 0.09185 mm/s and 0.0976 mm/s, respectively. This reveals that effects of mechanical erosion on hybrid rocket nozzles should be carefully considered and evaluated under conditions of high aluminum content.

Research on the Erosion of Gun Barrel Based on Vented Vessel Tests

The vented vessel test, as an alternation of the firing practice, is implemented to reconstruct the deterioration process of the gun barrel suffering the thermochemical erosion by propellant combustion gas. High pressure of over 300 MPa with a duration exceeding 20 ms is applied on the rifled specimen. A phase transition layer about 136 μm is observed by scanning electron microscopy (SEM) from the cross section of the test specimen. Some residual oxidation products of the iron can be detected by energy dispersive x-ray spectroscopy (EDS) on parts of the inner surface. A comprehensive erosion analysis is conducted, which estimates that the mass loss of the specimen is mainly attributed to the periodical formation and peeling of the chemical reaction layer on the bore surface. The most severely eroded part is located on the corner of the land. On the basis of the examined erosion mechanisms, a proper thermochemical erosion model is employed. The mass dissipation and the geometry evolution under continuous firing are simulated using finite element method (FEM). The simulation phenomenon shows good consistency with results of the experimental tests.

A Novel Fused SiO2 and h-BN Modified Quartz Fiber/Benzoxazine Resin Ceramizable Composite with Excellent Flexural Strength and Ablation Resistance.

Hypersonic vehicles encounter hostile service environments of thermal/mechanical/chemical coupling, so thermal protection materials are crucial and essential. Ceramizable composites have recently attracted intensive interest due to their ability to provide large-area thermal protection for hypersonic vehicles. In this work, a novel ceramizable composite of quartz fiber/benzoxazine resin modified with fused SiO2 and h-BN was fabricated using a prepreg compression molding technique. The effects of the fused SiO2 and h-BN contents on the thermal, mechanical, and ablative properties of the ceramizable composite were systematically investigated. The ceramizable composite with an optimized amount of fused SiO2 and h-BN exhibited superb thermal stability, with a peak degradation temperature and residue yield at 1400 °C of 533.2 °C and 71.5%, respectively. Moreover, the modified ceramizable composite exhibited excellent load-bearing capacity with a flexural strength of 402.2 MPa and superior ablation resistance with a linear ablation rate of 0.0147 mm/s at a heat flux of 4.2 MW/m2, which was significantly better than the pristine quartz fiber/benzoxazine resin composite. In addition, possible ablation mechanisms were revealed based on the microstructure analysis, phase transformation, chemical bonding states, and the degree of graphitization of the ceramized products. The readily oxidized pyrolytic carbon (PyC) and the SiO2 with a relatively low melting point were converted in situ into refractory carbide. Thus, a robust thermal protective barrier with SiC as the skeleton and borosilicate glass as the matrix protected the composite from severe thermochemical erosion and thermomechanical denudation.

Unified computational model of thermochemical erosion and mechanical wear in artillery barrel considering hydrodynamic friction

Erosion wear of the artillery barrel is divided into two primary categories: thermochemical erosion and mechanical wear. However, the majority of studies concerning this subject matter emphasize the former, and the latter has not been given enough consideration. To describe the coupling relationship of thermochemical erosion and mechanical wear, this article is inspired by the frictional behavior between the barrel and the projectile and proposes a material degradation model for thermochemical erosion considering frictional temperature rise. Under the coupling of the forced heat convection of high-temperature propellant gas and frictional heat, the friction state between the barrel and the projectile is changed from dry friction to hydrodynamic friction, resulting in a novel mechanical frictional wear model. Subsequently, numerical simulations of the thermochemical erosion and mechanical wear models are carried out. The results show that the erosion wear of the artillery barrel is divided into four regions along the axial direction: thermochemical erosion, thermochemical-mechanical erosion, transition, and mechanical wear regions. Four regions are concentrated in the interval of [0 mm, 500 mm], [500 mm, 1750 mm], [1750 mm, 4000 mm] and [4000 mm, 6800 mm], respectively.

Experiments of ablation characteristics for different nozzle materials and transient simulations on thermochemical erosion in hybrid rocket motors

This paper focuses on investigating ablation characteristics of different nozzle materials in hybrid rocket motors by firing tests and numerical simulations. Hybrid rocket nozzles with different ablation materials are designed and manufactured. Four firing tests with working time of 40 s are conducted, and 90% hydrogen peroxide and polyethylene are adopted. The test results indicate that erosion rates of T705 graphite, whole felt C/C composite, axial rod braided C/C composite, and carbon/ceramic composite are 0.045 mm/s, 0.022 mm/s, 0.03 mm/s, and 0.01 mm/s. Circumferentially uneven ablation is found in the nozzle throat of T705 graphite and C/C composite, and this is mainly due to asymmetric oxidizer injection, asymmetric combustion, and uneven material properties. Transient numerical simulations of 40 s on nozzle thermochemical erosion are carried out, and the regression process of fuel wall and nozzle wall is solved by a dynamic grid technique. The error of average throat erosion rate between simulation results and test results is only 1.82%. The evolution process of nozzle profile and flow field structure are exhibited, and coupling effects between the erosion rate and nozzle profile are obtained. Simulation results show that as the working time increases, protrusions and pits appear on the nozzle inner wall and gradually extend. The temperature of nozzle wall and nozzle erosion rate on the windward side is higher, while they are lower on the leeward side. Nozzle throat erosion rate history is divided into four stages, and time nonlinear characteristics of the throat erosion rate are revealed.

Investigation of the Thermochemical Erosion Properties of High-Strength Steel Surfaces in High-Temperature Propellant Gas

Investigation of the Thermochemical Erosion Properties of High-Strength Steel Surfaces in High-Temperature Propellant Gas

Numerical study of nozzle erosion in a hybrid rocket motor with wagon wheel fuel grain

Nozzle erosion directly affects the design quality of hybrid rocket motors, and it is a critical issue that restricts the practical application of hybrid rocket motors. In this paper, coupled numerical simulations of combustion flow field and thermochemical erosion of a graphite nozzle in a hybrid rocket motor with multi-port wagon wheel fuel grain are carried out. The results indicate that distributions of temperature, species and erosion rate in the flow field of hybrid rocket motor with wagon wheel grain show symmetrical characteristics related to the grain shape. The erosion rate decreases at first and then increases at the convergent section of throat insert, and it reaches the maximum value at the transition arc between convergent section and straight section of the throat. The maximum erosion rates at the central hole (position A) and outer edge of wheel holes (position B) are 0.0625 mm/s and 0.0902 mm/s, respectively. The erosion rate increases slowly in the straight section of the throat and it decreases gradually in the divergent section. Circumferentially inhomogeneous ablation occurs in the throat, and the erosion rate at the front end of throat straight section varies from 0.0484 mm/s to 0.0809 mm/s. The main oxidizing species causing thermochemical erosion are H2O and OH. At position A in the front end of throat straight section, erosion rates caused by H2O and OH are 66.50% and 30.48%, respectively. With the increase of oxidizer mass flow rate, the combustion chamber pressure increases linearly, and the erosion rate at position A in the front end of throat straight section gradually increases, but the growth rate decreases.

Surface damage evolution of artillery barrel under high-temperature erosion and high-speed impact

Thermochemical erosion and mechanical wear are the primary sources of surface damage in artillery barrel chambers, severely restricting the interior ballistic characteristics and service life of the barrel weapon. This paper proposes a general surface damage computational model, which contains three sub-models: collision wear, melting exfoliation, and high-speed jet wear. The combination of the three sub-models can predict the surface damage of mechanical structures caused by the coupling of thermochemical erosion and mechanical wear. The contact force model to describe collision behavior is first proposed, and the collision wear model can be obtained based on the contact force model. Moreover, the temperature distribution of the barrel chamber is calculated, by this the melting exfoliation model can be obtained. Considering that melting exfoliation and collision wear have the non-negligible effect on the attack angle of high-speed jet, this paper equates melting exfoliation and collision wear to the variation of attack angle size and investigates the high-speed jet wear of the barrel chamber. The experimental research of the surface damage on the barrel chamber is organized, and the detailed assessments show that the general surface damage computational model has a good agreement with experimental data.

Research on thermochemical erosion and thermal protection properties of multiple interface nozzles in long-time working hybrid rocket motors

To improve the ablation resistance under long-time working conditions, a multiple interface nozzle with a carbon ceramic throat cap and a copper infiltrated tungsten throat insert is designed. Firstly, a transient numerical model on thermochemical erosion (considering surface reactions of carbon and tungsten) of the multiple interface nozzle in a hybrid rocket motor is established, and the regression of nozzle inner profile is simulated by adopting a dynamic grid technique. Then a 200 s firing test of the full-scale hybrid rocket motor with the multiple interface nozzle is conducted, and 98% hydrogen peroxide and hydroxyl-terminated polybutadiene based fuel are adopted. Erosion steps are formed at the interface of the carbon ceramic and copper infiltrated tungsten, and its formation mechanism is discussed. The erosion step height on the windward side of the throat insert is larger than that on the leeward side of the throat insert. The nozzle inner profile after the test agrees well with the simulation results, and the error of the nozzle throat diameter between the simulation results and test data is about 3.45%, which verifies the accuracy of numerical models. Finally, effects of erosion steps on the ablation characteristics and thermal protection properties are studied by numerical simulations. The results indicate that the erosion rate on the leeward side is much lower than that on the windward side. On the leeward side, the obvious radial diffusion of the gas occurs and the erosion rate increases with the increase of the erosion step height. Local vortices at the position of erosion steps will improve the heat transfer coefficient. When the erosion step height increases, the temperature on the outside surface of the nozzle shell improves, and it is increased by 38.3 K on the shell surface in the nozzle throat at t = 200 s. Research findings in this paper can provide important support for the engineering application of hybrid rocket motors with multiple interface nozzles.

Sedimentary and crustal structure of eastern North China from joint inversion of Rayleigh wave phase velocity and ellipticity and its implication for magmatism

Understanding the tectonic evolution of the North China Craton and its destruction mechanism requires the knowledge of eastern North China's fine crustal velocity structure. Using the two-year record of 342 ChinArray stations deployed in eastern North China, we obtain the Rayleigh wave phase velocity via ambient noise interferometry and Rayleigh wave ellipticity from ∼1000 teleseismic events. High-resolution sedimentary thickness and crustal 3D S-wave velocity structure are obtained by jointly inverting these observations. The results show that the Bohai Bay Basin is infilled with thick sediments and the Central Bohai Sea is the current depocenter with sedimentary thickness up to about 6 km. The crust and uppermost mantle beneath the Bohai Bay Basin are characterized by low velocity, indicating a high internal temperature of the crust. An upwelling of mantle thermal material under the crust of the Bohai Bay Basin continuously modifies the crust, suggesting that bottom-up thermochemical erosion is likely the primary control factor of crustal modification and thinning in this area. The uplift areas around the basin generally exhibit high velocity with weaker crustal modification, showing the heterogeneity of craton modification. Moreover, localized low-velocity zones observed beneath the Chifeng Volcanos, Dalainor Volcanos, and Kuandian Volcanos indicate the residual magmatism beneath these Quaternary volcanos. Furthermore, the magmatism beneath the Chifeng and Dalainor Volcanos shares a common magmatic source.

Thermal and rheological structure of lithosphere beneath Northeast China

We investigate 3-D thermal and rheological structures of the lithosphere beneath Northeast China using detailed P- and S-wave velocity models following mineral physics as well as geothermal methods. Small-scale temperature changes and thermal lithosphere thickness variations between different tectonic blocks are revealed. Our results show that strong lateral heterogeneities exist in the lithospheric thermal structure and rheological structure on both sides of the North-South Gravity Lineament (NSGL). The Changbai volcanic area and the central part of the Songliao Basin in the eastern side of the NSGL exhibit higher temperatures, thinner thermal lithosphere and lower rheological strength, which are closely associated with the western Pacific plate subduction under the Eurasian continent, resulting in upwelling of wet and hot asthenospheric material above the stagnant Pacific slab in the mantle transition zone. The thermo-chemical erosion of the upwelling asthenospheric material may induce delamination of partial lithosphere under the Songliao Basin. In addition, the western and southern edges of the Songliao Basin are characterized by lower temperature, thicker thermal lithosphere and higher rheological strength, which may indicate a relatively stable lithosphere. The Halaha and Abaga volcanic areas in the western side of the NSGL exhibit higher temperature, thinner thermal lithosphere and lower rheological strength, which could be caused by small-scale upwelling of hot asthenospheric material associated with delamination of partial lithosphere beneath the Songliao Basin.

United computational model for predicting thermochemical-mechanical erosion in artillery barrel considering friction behavior

Artillery barrel erosion is mainly divided into two categories, namely thermochemical erosion and mechanical wear. However, most current research on this topic focuses on the former, and lacks sufficient attention to the latter. To describe the coupling relationship of thermochemical-mechanical erosion, this paper is inspired by the friction behavior between barrel and projectile, and proposes a material degradation model of thermochemical erosion considering frictional temperature rise. The change in the friction state caused by the temperature rise in a barrel is characterized by the friction coefficient formula, and updating the interior ballistic movement, results in a novel mechanical friction wear model. Moreover, a mechanical collision wear model is derived using the impact abrasion theory. The followed finite element simulations demonstrate that these proposed quantification models are capable of describing the artillery barrel erosion characteristics during the interior ballistic process more accurately. Good agreement between the numerical simulation and the actual rifling erosion conditions is achieved. The larger erosion is mainly located at the initial part of the rifling and the muzzle, which are about 1.50 mm and 0.45 mm respectively after launching 500 projectiles.

Transient investigation of nozzle erosion in a long-time working hybrid rocket motor

Nozzle erosion is a common problem in a hybrid rocket motor with the passive thermal protection structure. Nozzle profile and erosion rate distribution are changing with time due to the chemical erosion. Serious erosion greatly influences the performance of the hybrid rocket motor. This paper is aimed to analyze the characteristics of nozzle erosion during the firing process. For this purpose, an unsteady numerical model of carbon-based nozzle erosion is established. The thermochemical erosion of nozzle is simulated coupled with the flow field. A dynamic grid technique is adopted to simulate the regression process of the nozzle surface. Based on this model, numerical simulations on a hydrogen peroxide(HP)/hydroxyl-terminated polybutadiene (HTPB) hybrid motor have been performed in a long-time working process. To validate the numerical results, a full-scale hybrid rocket motor is tested. The simulated nozzle erosion rate is about 0.069 mm/s in the steady state simulation, which agrees well with the test data (0.072 mm/s). The material properties of the carbon ceramic composite are affected by the high-temperature gas and suffering performance degradation in the firing process. Both of the combustion chamber pressure and oxidizer to fuel ratio have great influence on the erosion rate.

An Experimental Study on the Ablation Properties of Carbon/Carbon Composites Using Thermal Plasma

The ablation properties of two carbon/carbon (C/C) composites currently considered as thermal protection materials for radioisotope thermoelectric generators (RTGs) were investigated using a plasma wind tunnel with a heat flux between the range of 2–4 MW/m2. The ablation properties were identified through an analysis of erosion rates and microstructures after testing. During ablation, erosion reactions of the matrix were faster than those of fibers and pores, and the defects and cracks between the fibers and matrix grew. The fibers eroded from their outer surface and ablation led to the formation of sharp tapered tips. Lower density C/C composites appeared to lose more matrix than higher density C/C composites. The erosion rate increased with heat flux. The ablation properties were compared with the test results using a vacuum plasma spray (VPS) facility and an E-beam facility. It was shown that both thermochemical and thermomechanical erosion occurred via oxygen in the plasma flow, and a rapid high-pressure heat stream occurred in tests using the plasma wind tunnel while only thermal ablation occurred in tests using the VPS and E-beam facilities.

Lateral variations in the Unit 7\u20138 boundary zone of the Rum Eastern Layered Intrusion, NW Scotland: implications for the origin and timing of Cr-spinel seam formation

The Rum Layered Suite, NW Scotland, hosts Cr-spinel seams at the bases of peridotite–troctolite macro-rhythmic units in the eastern portion of the intrusion. Here, we present detailed field observations together with microstructural and mineral chemical analyses for the Unit 7–8 Cr-spinel seam and associated cumulates in the Eastern Layered Intrusion. Detailed mapping and sampling reveal significant lateral variations in the structural characteristics and mineral compositions of the Unit 7–8 boundary zone rocks. Although the Cr-spinel seam is laterally continuous over ~ 3 km, it is absent towards the centre and the margins of the intrusion. The compositional characteristics of Cr-spinel and plagioclase vary systematically along strike, exhibiting a chemical evolution towards more differentiated compositions with increasing distance from the main feeder conduit of the Rum intrusion; the Long Loch Fault. On the basis of our combined datasets, we propose that the upper part of the troctolite, the anorthosite layer underlying the Cr-spinel seam and the seam itself formed during a multi-stage magma replenishment event. The stages can be summarised as follows: (1) peridotite schlieren and anorthosite autoliths formed following melt infiltration and cumulate assimilation in the crystal mush of the Unit 7 troctolite. (2) The anorthosite layer then formed from the Unit 7 troctolite crystal mush by thermal erosion and dissolution due to infiltrating magma. (3) Subsequent dissolution of the anorthosite layer by new replenishing magma led to peritectic in situ crystallisation of the Unit 7–8 Cr-spinel seam, with (4) continued magma input eventually producing the overlying Unit 8 peridotite. In the central part of the Rum Layered Suite, the aforementioned assimilation of the troctolitic footwall formed the anorthosite layer. However, the absence of anorthosite in close proximity to the Long Loch Fault can be explained by enhanced thermochemical erosion close to the feeder zone, and its absence close to the margins of the intrusion, at maximum distance from the Long Loch Fault, may be due to cooling of the magma and loss of erosion potential. In line with other recent studies on PGE-bearing chromitites in layered intrusions, we highlight the importance of multi-stage intrusive magma replenishment to the formation of spatially coupled anorthosite and Cr-spinel seams, as well as the lateral mineral chemical variations observed in the Unit 7–8 boundary zone cumulates.