Ignition Resistance Research Articles

Microstructure and mechanical properties of new Mg-Zn-Y-Zr alloys with high castability and ignition resistance

Microstructure and mechanical properties of new Mg-Zn-Y-Zr alloys with high castability and ignition resistance

Hot deformation behavior of an ignition resistance Mg–6Zn-0.6Zr-1.2Ca magnesium alloy

The addition of Ca could enhance the ignition point of magnesium alloys but impairing their workability, so it is essential to study the hot deformation behavior of new Ca-containing ignition resistance magnesium alloys. The hot deformation behavior of a new ignition resistance Mg–6Zn-0.6Zr-1.2Ca alloy was investigated by compression experiment in the temperature range of 240 °C–360 °C, strain rates of 10−3 s−1-1 s−1 and height reduction of 10%–60%. The true stress-strain curves show that flow stress decreases as the deformation temperature increases or the strain rate decreases. Microstructure analysis shows that higher temperatures and lower strain rates are favorable for DRX, while higher strain rates promote the fragmentation of the Ca2Mg6Zn3 phase. Meanwhile, the existence of Ca2Mg6Zn3 phase make the DRX process be dominated by the particle-induced subgrain nucleation mechanism. By superposition of the power dissipation map and the instability map, a hot processing map of true strain of 0.6 is generated. According to analyses on the processing map and microstructure evolution, the instability of processing map can be attributed to the greater dislocation motion resistances, insufficient DRX, and Ca2Mg6Zn3 phase with low-melting point. Conversely, the optimal processing parameters for the alloy were determined as 280–360 °C/0.001–0.01 s−1 in safe zone with a high η above 0.3, which can be due to the apparent DRX and good deformation coordination.

Evaluation of the Impact of Parylene C Deposition Method on the Functional Properties of Fabrics.

The article presents the results of research on the impact of the use of an original, innovative method of deposition of Parylene C on the functional properties of fabrics with various potential applications (e.g., thermal and chemical protective clothing, packaging, covers and others). Verification of the effects of the method used was based on interdisciplinary research taking into account the impact of coating fabrics on changes in their structure (micro-CT), surface properties (contact angle), barrier properties (water and chemical liquid wetting), electrostatic properties (charge decay), biophysical properties describing heat and mass transfer (by the Alambeta system and thermal imaging) and flammable properties. Four fabrics made of synthetic organic fibres (meta-aramid, para-aramid) and natural inorganic fibres (basalt) were selected for testing. Given the complex structure of textile substrates, the results confirmed that the two assumed thicknesses of the Parylene C coating were consistent with the actual measurements. The findings indicated that the coatings significantly reduced water and acid absorption in the fabrics compared to unmodified ones. Thermal insulation property tests revealed that coated fabrics exhibited higher thermal conductivity than unmodified fabrics. Additionally, the presence of Parylene C on aramid fabrics resulted in a modest increase in their ignition resistance.

Mg-based alloys with Y, Ca and Al reaching exceptional ignition resistance and suppressed flammability

Magnesium alloys are increasingly pivotal in automotive and aerospace engineering due to their superior strength-to-weight ratio. This rising prominence necessitates advancements in their mechanical characteristics, such as tensile strength, ductility, and fatigue endurance, alongside enhanced control over their interaction with oxygen. A critical phenomenon in this context is the ignition of magnesium in oxygen-rich environments at high temperatures. This exothermic reaction induces a rapid temperature surge, potentially reaching 3000 °C, leading to the catastrophic disintegration of magnesium alloy components. Consequently, research in magnesium technology also focuses on augmenting the ignition threshold and diminishing the material's combustibility. This expansion in the application scope for magnesium alloys in the aviation and aerospace sectors hinges on developing novel alloy compositions. Elements like yttrium (Y), rare-earth elements, and calcium (Ca) are under exploration for their potential to bolster ignition resistance in magnesium alloys. However, the impact of these elements on ignition and flammability is highly dependent on their concentration and the overall alloy chemistry. Four magnesium alloys, integrating yttrium, calcium, and aluminium – a conventional element in commercial alloys – were synthesised in the study under discussion through casting and thermal processing. These alloys were methodically examined for microstructural evolution and their resistance to ignition and flammability. The results demonstrated that when appropriately balanced with yttrium, aluminium is a viable alloying element in magnesium alloys without significantly compromising ignition resistance. The alloy WAX211 exhibited the highest ignition temperature of 940 °C, attributed to the synergistic effects of calcium and yttrium and the formation of a highly stable protective oxide layer.

Preparation of novel gel foam and its fire suppression performance against gasoline pool fires

The phenomenon of re-ignition after extinguishing tank fires poses a significant challenge for firefighting and rescue operations. In this study, a gel foam was prepared using linseed gum as the gelling agent and sodium tetraborate as the cross-linking agent. By analyzing the foaming performance of the gel foam, the optimal formulation for the gel foam was determined. Subsequently, microscopic structural observations and thermal stability tests were conducted on this material. A comparison of the firefighting performance between the gel foam and aqueous film-forming foam (AFFF) on extinguishing gasoline pool fires was also carried out. The results indicate when the foaming agent, consisting of coconut oil glucoside (APG0814) and fatty alcohol polyoxyethylene ether (AEO-9), is used in a 9:1 ratio with a mass fraction of 0.4 wt%. Furthermore, by introducing 0.35 wt% concentration of linseed gum and 0.02 wt% concentration of sodium tetraborate, the gel foam exhibits a foaming expansion ratio of 6.5, a half-life of 203 min, and a comprehensive value of 989.63, which represents the best performance. The gel foam and the AFFF exhibit relatively similar extinguishing effectiveness, with respective extinguishing times of 108s and 95s.Further analysis of the gel foam's resistance to re-ignition reveals that the gel foam demonstrates 25 % and 90 % ignition resistance times of 425s and 573s, respectively, representing a significant enhancement of 66.02 % and 104.64 % compared to the AFFF. These results indicate that the novel gel foam possesses excellent resistance to re-ignition, reducing the risk of fire rekindling in liquid fire scenarios. This research serves as a valuable reference for the development of environmentally friendly and re-ignition-resistant gel foam for extinguishing liquid fires.

Metal-Coordinated Epoxy-Amine Composition with Reduced Fire Risk: Elaboration, Thermal and Ignition Resistance

Metal-Coordinated Epoxy-Amine Composition with Reduced Fire Risk: Elaboration, Thermal and Ignition Resistance

Comparison of Shallow (−20 °C) and Deep Cryogenic Treatment (−196 °C) to Enhance the Properties of a Mg/2wt.%CeO2 Nanocomposite

Magnesium and its composites have been used in various applications owing to their high specific strength properties and low density. However, the application is limited to room-temperature conditions owing to the lack of research available on the ability of magnesium alloys to perform in sub-zero conditions. The present study attempted, for the first time, the effects of two cryogenic temperatures (−20 °C/253 K and −196 °C/77 K) on the physical, thermal, and mechanical properties of a Mg/2wt.%CeO2 nanocomposite. The materials were synthesized using the disintegrated melt deposition method followed by hot extrusion. The results revealed that the shallow cryogenically treated (refrigerated at −20 °C) samples display a reduction in porosity, lower ignition resistance, similar microhardness, compressive yield, and ultimate strength and failure strain when compared to deep cryogenically treated samples in liquid nitrogen at −196 °C. Although deep cryogenically treated samples showed an overall edge, the extent of the increase in properties may not be justified, as samples exposed at −20 °C display very similar mechanical properties, thus reducing the overall cost of the cryogenic process. The results were compared with the data available in the open literature, and the mechanisms behind the improvement of the properties were evaluated.

Enhancing Multiple Properties of a Multicomponent Mg-Based Alloy Using a Sinterless Turning-Induced Deformation Technique

A magnesium-based multi-component alloy (MCA), Mg70Al18Zn6Ca4Y2, was successfully synthesized using the Turning-Induced Deformation (TID) method, with promising improvements in multiple properties such as damping capabilities, hardness (11% to 34% increase), and strength (5% to 15% increase) over its conventional cast and extruded equivalent which has already been established as a high-performance MCA exhibiting superior mechanical properties over other Mg-based materials while retaining acceptable ductility. This new TID-based MCA comes only at a slight compromise in the aspects of ductility, ignition resistance, and corrosion resistance, which was previously observed in other TID-based materials. In addition, the general microstructure and secondary phases of this MCA were retained even when using the TID method, with only minimal porosity (<1%) incurred during the process. Furthermore, the ignition temperature of the TID Mg70Al18Zn6Ca4Y2 remained very high at 915 °C, positioning it as a potential Mg-based material suitable for aerospace applications with a high ignition resistance. This is tantamount to a successful application of TID to yet another class of Mg-based materials and opening the door to future explorations of such materials.

Combustion and emissions characteristics of ammonia/diesel dual-fuel engine with high premixed fractions in different injection modes

The performance of the ammonia/diesel dual-fuel (ADDF) engine still suffers from low indicated thermal efficiency (ITE) and misfiring with higher premixed fractions of ammonia. To improve the performance of the ADDF engine, this study compared two diesel injection modes, i.e., constant injection duration (CID) and constant injection rate (CIR) modes under high premixed fractions (fNH3). This was achieved by conducting numerical simulations using the CONVERGE solver coupled with a newly developed skeletal mechanism of ammonia/n-heptane. In the simulation, the fNH3 was increased from 0.4 to 0.9 at an interval of 0.1 with an engine speed of 910 rpm. Subsequently, the combustion and emissions characteristics of ADDF engines were analyzed. The results show that due to the ignition resistance of ammonia and the lower diesel injection pressure in the CID mode, the combustion deteriorates as fNH3 increases. Moreover, CO, N2O, and greenhouse gas (GHG) emissions increase with the increase of fNH3 under CID mode, while NOx emissions remain unchanged. In contrast, the CIR mode could increase the injection pressure of diesel in the cylinder thereby overcoming the negative effects of the ignition resistance of ammonia in conditions with high fNH3. Compared with the CID mode, the CIR mode can not only realize higher peak pressure, temperature, and heat release rate, but also improve the ITE with low ringing intensity, and reduce CO and GHG emissions. However, the NOx emissions of the engine in the CIR mode are higher due to the elevated combustion temperature.

Microstructure and properties of the GEWZ522K casting magnesium alloy based on the Mg–Gd–Nd–Y–Zn–Zr system

The article discusses the solidification and phase composition of the (wt.%) Mg–4.8Gd–2.1Nd–1.6Y–0.4Zn–0.6Zr (GEWZ522K) casting alloy. It is demonstrated that in the as-cast state, the alloy structure comprises primary zirconium particles, dendrites of the magnesium solid solution (αMg), and eutectic intermetallic phases located between dendritic branches. Following solution heat treatment at t = 530±5 °C, the alloy transitions into a single-phase state and can be significantly strengthened through artificial aging after quenching. It is recommended to apply alloy aging at t = 250 °C for 8–10 h or at t = 200 °C for 15–18 h. This approach leads to the maximum strengthening of the alloy, with the best mechanical properties achieved for the alloy aged at t = 250 °C. Regardless of the aging method used, the ultimate tensile strength (UTS) of the samples surpasses 300 MPa, which significantly exceeds that of commercial casting alloys according to GOST 2856-79. The measured corrosion rate for the GEWZ522K alloy is 7.5±0.4 mm/year, that slightly higher than that for the less alloyed commercial alloy ML10 (approximately 2.5 mm/year) tested under similar conditions. Furthermore, the alloy was subjected to tests for ignition resistance when in contact with air. It was observed that with continuous airflow over the specimen’s surface, ignition centers appear at t = 625 °C due to the breakdown of the oxide film, causing the alloy to nearly completely melt. Therefore, the GEWZ522K alloy can be employed as a high-strength casting alloy. However, during the operation of cast parts, particular attention must be paid to safeguarding the surface of these parts against corrosion.

Fuel effects on foams generated using different surfactants

Aqueous film-forming foams (AFFF) that contain perfluoro-alkyl substance (PFAS) surfactants are being banned due to their bio-persistence and bio-accumulative behavior. As a result, new surfactants to replace the PFAS-based surfactants are being sought. The focus of this study is to explore the impact of surfactant types on the resistance of fuel transport through the foam. Fuel transport through the foam was measured using static foam ignition tests on a typical hydrocarbon fuel (n-heptane) and an aromatic fuel (trimethylbenzene). The ignition resistance of four different surfactant types as well as AFFF. Experiments in a Dynamic Foam Analyzer were also conducted to relate the ignition resistance to the response of the foam (bubble size, interface structure) at the foam-fuel interface. The shortest ignition times were measured with n-heptane beneath the foam. Foams with the lowest ignition times displayed void formation and a more variable interface compared with the more ignition-resistant foams.

Ignition Resistance of Pure Mg, ZM5 and ZM6 Magnesium Alloys

The use of magnesium alloys in aerospace is relatively restricted by their poor ignition resistance performance. A continuous heating test was conducted to investigate the ignition resistance of pure Mg, ZM5, and ZM6 magnesium alloys with different alloying elements. It was found that alloying elements greatly influenced the ignition resistance of magnesium alloys. With about 2% addition of Nd rare earth element, ZM6 had a higher ignition temperature than pure Mg. In comparison, the ignition temperature of ZM5, which contains mainly about 8% Al alloying element, was lower than that of pure Mg. Analysis of high-temperature surface oxide film reveals that the higher ignition temperature of ZM6 resulted from a protective Nd2O3 oxide film formed on the oxidized surface. Alloying with rare earths can improve the ignition resistance of magnesium alloys.

Ignition Resistance of Wood Building Structures Exposed to a Firebrand Shower

Ignition Resistance of Wood Building Structures Exposed to a Firebrand Shower

Development of high-strength magnesium alloys with excellent ignition-proof performance based on the oxidation and ignition mechanisms: A review

High reactivity and ease of ignition are the major obstacles for the application of Mg alloys in aerospace. Thus, the ignition mechanisms of Mg alloys should be investigated systematically, which can guide the ignition-proof alloy design. This article concludes the factors influencing the ignition resistance of Mg alloys from oxide film and substrate microstructure, and also the mechanisms of alloying elements improving the ignition resistance. The low strength is another reason restricting the development of Mg alloys. Therefore, at the last section, Mg alloys with the combination of high strength and good ignition-proof performance are summarized, including Mg-Al-Ca based alloys, SEN (Mg-Al-Zn-Ca-Y) alloys as well as Mg-Y and Mg-Gd based alloys. Besides, the shortages and the future focus of theses alloys are also reviewed. The aim of this article is to promote the understanding of oxidation and ignition mechanisms of Mg alloys and to provide reference for the development of Mg alloys with high strength and excellent ignition-proof performance at the same time.

Extrusion limit diagram of AZ91–0.9Ca–0.6Y–0.5MM alloy and effects of extrusion parameters on its microstructure and mechanical properties

Abstract An AZ91–0.9Ca–0.6Y–0.5 MM (AZXWMM91100) alloy, which has higher corrosion resistance, ignition resistance, and extrudability than a commercial AZ91 alloy, has been developed recently. In this study, the AZXWMM91100 alloy is extruded at various temperatures (300–400 °C) and ram speeds (1–14.5 mm/s), and the cracking behaviors, microstructure, and tensile properties of the extruded materials are systematically analyzed. On the basis of the pressure limit and surface and internal cracking limit, the extrusion limit diagram providing a safe extrusion processing zone is established. All of the materials extruded at temperatures and speeds within the safe extrusion processing zone have high surface quality and moderate tensile ductility with an elongation higher than 10%. Moreover, they have a fully recrystallized grain structure and contain undissolved particle stringers arranged parallel to the extrusion direction. The grain size of the extruded material does not show any relationship with the Zener–Hollomon parameter (Z). However, the yield strength (YS) of the extruded material is inversely proportional to the logarithm of the Z value, and their relationship is expressed as YS = −31.2•log(Z) + 536. These findings may broaden the understanding of the AZXWMM91100 alloy with excellent chemical and physical properties and provide valuable information for the development of high-performance extruded Mg products using this alloy.

Evaluation of potential toxicity of smoke from controlled burns of furnished rooms – effect of flame retardancy

ABSTRACT It has been reported that incorporation of fire retardants into home furnishings and electronics increases the toxicity of smoke produced during combustion in house fires. Studies have been limited to exercises in analytical chemistry but the biological effects of emissions, particularly regarding chronic toxicity, have not been investigated. The combustion of furnishings with and without chemical flame retardants (FR) regarding (1) ignition resistance and fire progression, (2) chemical composition of smoke (analytical chemistry), and (3) toxicity was compared. Data demonstrated that flame retarded furnishings slowed the generation of toxic levels of acutely toxic gases. The potential chronic toxicity of smoke was assessed using the ToxTracker® assay. Smoke samples from rooms with less flame retarded furnishings exhibited a lesser response in this assay than smoke samples from rooms with flame retarded furnishings. Chemicals associated with activation of the aryl hydrocarbon receptor (AHR), namely benzo[b]fluoranthene, benzo[a]anthracene, benzo[a]pyrene, chrysene, and indeno[1,2,3-cd]pyrene, were not found in smoke from more flame retarded furnished rooms, but were present only in smoke from rooms with less flame retarded furnishings. In conclusion, smoke resulting from combustion of flame retarded furnishings did not increase indicators of potential chronic toxicity hazards relative to non-flame retarded furnishings.

Microstructure, Mechanical and Ignition Characteristics of Si3N4 Reinforced Magnesium Matrix Nanocomposites

Lightweight magnesium-based materials have received attention in the automobile sector as a solution to minimize fuel consumption and greenhouse gas emissions. Magnesium has great weight-reduction potential in the aerospace sector, but its low ignition temperature limits its utilization. Improving magnesium’s ignition resistance is critical for aerospace applications. The present study developed Mg/Si3N4 nanocomposites to improve the ignition resistance to address this limitation. The nanocomposites were prepared by ultrasonically-assisted stir casting with 0.5, 1, and 1.5 vol% Si3N4 nanoparticles. The effect of Si3N4 nanoparticles on the ignition and compression characteristics was examined. SEM micrographs showed the homogeneous dispersion of Si3N4 nanoparticles with negligible clustering. Notably, the nanocomposites’ ignition resistance was increased by increasing the vol% of the Si3N4 nanoparticles. Adding 1.5 vol% Si3N4 nanoparticles resulted in the highest ignition temperature of 614 °C, 34 °C higher than pure magnesium. Similarly, the compressive properties were enhanced with the progressive addition of Si3N4 nanoparticles. The inclusion of 1.5 vol% Si3N4 nanoparticles resulted in a maximum compressive yield strength of 118 MPa and ultimate compressive strength of 323 MPa.

Non-ignitable dilute Mg–0.36Al–1CaO (wt.%) alloy with high compressive strength

ABSTRACT The industrialisation of Mg alloys is hindered by low strength and ignitability. In this way, compressive strength is of prime interest, and unfortunately, commercial Mg castings have compressive yield strength less than 200 MPa. We have developed a non-ignitable Mg–0.36Al–1CaO (wt.%) alloy by ECO processing route that, despite its leanness (<1 wt.% total alloying content), has a compressive yield strength of higher than 200 MPa in all three different conditions of as-cast, T4, and peak-aged T6, showing the viability of both age hardening, and solid-solution strengthening accompanied by short-range order. The chemical analysis revealed that the reaction between 1 wt.% of added CaO and the melt led to ~0.4 wt.% alloyed Ca (Ca/Al mass ratio is ~1). The protective effect of alloyed Ca, enabled casting without extra protections (gases or salt) with no sign of ignition. Microstructural evolution was studied by SEM and EDS in conjunction with thermodynamic calculations. Comparison of the compressive yield strength of this alloy (in as-cast, T4, and peak-aged T6 conditions) with that of commercial alloys showed this alloy has the highest strength, with the added benefits of lower production costs and ignition resistance, bestowed by utilising cheap CaO.

Control of ZM5 alloy ignition via PEO/aluminum phosphate composite coating

A composite coating consisting of the plasma electrolytic oxidation (PEO) and aluminum phosphate layer was fabricated to improve the ignition resistance of ZM5 alloy. The influences of PEO coating and PEO/aluminum phosphate composite coating on the ignition resistance of ZM5 alloy were investigated by torch ignition and non-isothermal oxidation test. The ZM5 alloy with PEO/aluminum phosphate composite coating possesses the best ignition resistance and does not ignite when exposes to flame for 20 min, about 16 min longer than that of ZM5 alloy with PEO coating, and about 18 min longer than that of bare ZM5 alloy. The ignition protection was achieved through synergetic combination increased oxidation resistance, high strengthening and thermal expansion coefficient match of the composite coating. The incombustible ceramic component and metallurgical bond to the substrate endow the PEO coating with a self-extinguishing property. In addition, three characteristic stages (protective oxidation, non-protective oxidation and burning) of ZM5 alloy and its coating were identified based on the non-linear mass gain behaviors at different temperatures. The ZM5 alloy with PEO/aluminum phosphate composite coating had higher non-protective oxidation initial temperature (605 °C) than 437 °C of the bare ZM5 alloy. Meanwhile, the non-protective oxidation energy of the ZM5 alloy coated with PEO/aluminum phosphate composite coating was remarkably improved from 61 kJ/mol to 136 kJ/mol.

Development from Alloys to Nanocomposite for an Enhanced Mechanical and Ignition Response in Magnesium

The current study reports on the evolution of microstructure, variations in compressive properties and the ignition resistance of Mg through compositional variation, using alloying elements and nanoreinforcement. The alloys were designed with the use of a singular alloying element, Ca, and a binary alloying element, Ca+Sc, to develop Mg1Ca (wt.%) and Mg1Ca1Sc (wt.%) alloys. B4C nanoparticles were addedas the reinforcement phase in the Mg1Ca1Sc alloy to create the Mg1Ca1Sc/1.5B4C (wt.%) nanocomposite. The most effective compressive properties and level of ignition resistance was displayed by the developed composite. The grain sizes were significantly reduced in the Mg alloys (81%) and the composite (92%), compared with that of the Mg. Overall, the microstructural features (i.e., grain refinement, the formation of favorable intermetallic compounds, and hard reinforcement particles with an adequate distribution pattern) enhanced both the compressive strength and strain of the alloys and the composite. The ignition resistance was progressively increased from the alloys to the nanocomposite, and a peak ignition temperature of 752 °C was achieved in the composite. When compared with the ignition resistant of Elektron 21 (E21) alloy, which met the Federal Aviation Administration (FAA) requirements, the Mg1Ca1Sc/1.5B4C nanocomposite showed a higher specific yield strength and better ignition resistance, asserting it as a potential candidate material for lightweight engineering applications, including aerospace and defense sectors.