Ignition Resistance Research Articles

Development of Fireproof Textile Materials Safe on Contact with Human Skin

The issues of obtaining fireproof textile materials that do not cause negative effects upon contact with human skin using surface treatment are covered. The basic formulations of the compositions most frequently used to produce fireproof fabrics are considered. The possibility of developing a composition with optimal properties based on well-known flame retardants by selecting the type and amounts of stabilizers has been studied. The optimal formulation of a flame-retardant impregnating composition is developed, providing resistance to ignition and safe when in contact with human skin. The results of experimental studies of fabrics treated with the developed composition are given, namely: assessment of ignition resistance, smoke-forming ability, toxicity of combustion products, toxicological and hygienic characteristics of the effects on a living organism.

Combustion Microstructures and Frictional Ignition Resistance of Ti-6Al-4V Titanium Alloy

The effects of the contact pressure Pfric and the oxygen concentration c0 on the ignition resistance of Ti-6Al-4V were studied by friction in oxygen-enriched atmosphere. The relationship of Pfric-c0 was built to quantitatively describe the ignition resistance, the combustion microstructures were investigated by XRD, SEM and EDS. Further, the principle of improving the ignition resistance was proposed. It indicates that the relationship of Pfric-c0 obeys parabolic law. The c0 decreases by 4% when the Pfric increases from 0.1MPa to 0.25MPa, manifesting that the ignition resistance depends on c0 strongly (or equivalent flow pressure Peq). The ignition resistance of Ti-6Al-4V is 42.9% of that of TB12. When Peq varies from 0.1~0.5MPa, the critical ignition temperature Т* is approximate to 568~461K. Violent sparks form during frictional ignition. The low ignition resistance of Ti-6Al-4V probably results from not only the composite oxides of TiO2, Al2O3 and V2O5 generating during ignition which could not prevent the rapid interaction between Ti and O, but also the Al and V elements in the heat-affected zone which could not stop or slow the massive diffusion of O towards the alloy.

Enhancement of thermal, mechanical, ignition and damping response of magnesium using nano-ceria particles

Magnesium (Mg)-based nanocomposites owing to their low density and biocompatibility are being targeted for transportation and biomedical sectors. In order to support a sustainable environment, the prime aim of this study was to develop non-toxic magnesium-based nanocomposites for a wide spectrum of applications. To support this objective, cerium oxide nanoparticles (0.5 vol%, 1 vol%, and 1.5 vol%) reinforced Mg composites are developed in this study using blend-press-sinter powder metallurgy technique. The microstructural studies exhibited limited amounts of porosity in Mg and Mg-CeO2 samples (< 1%). Increasing presence of CeO2 nanoparticles (up to 1.5 vol%) led to a progressive increase in microhardness, dimensional stability, damping capacity and ignition resistance of magnesium. The compressive strengths increased with the increasing addition of the nanoparticles with a significant enhancement in the fracture strain (up to ~48%). Superior energy absorption was observed for all the composite samples prior to compressive fracture. Further, enhancement in thermal, mechanical and damping characteristics of pure Mg is correlated with microstructural changes due to the presence of the CeO2 nanoparticles.

A strong and deformable in-situ magnesium nanocomposite igniting above 1000\u2009\xb0C

Magnesium has been trending of late in automobile, aerospace, defense, sports, electronic and biomedical sectors as it offers an advantage in light-weighting. In aluminum, titanium, and steel dominated aerospace and defense sectors, applications of Mg were banned/restricted until recently due to perceived easy ignition and inability to self-extinguish immediately. Strength is generally inversely related to ductility, weak texture and unrelated to ignition resistance, making it challenging to optimize all four concurrently in a material. We address this challenge by designing a low density (~1.76 g.cm−3) in-situ Mg nanocomposite. It is a resultant of a sequence of in-situ reactions during melt processing and extrusion. The in-situ formed Y2O3 nanoparticles exhibit coherency with matrix and lead to development of large amount of elastic and plastic strain fields around them. These nanoparticles and secondary phases (Mg2Ca and Mg2Y) are responsible for the nanocomposite’s high tensile strength (~343 MPa). A weak texture mediated tensile ductility of 30% and compressive failure strain of 44% is observed. Further, the ignition temperature increased to 1045 °C (near the boiling point of Mg) due to the formation of protective surficial oxide layers aided by the presence of insulating Y2O3 nanoparticles, rendering the nanocomposite outperform other traditional commercial Mg-based materials.

Effects of Neodymium and Calcium on the Thermal Stability of AZ71 Magnesium Alloys

The effects of an addition of 0–2 wt% Nd on thermal stability of 0–3 wt% Ca-containing modified AZ71 magnesium alloys was investigated. The ignition temperature was found to increase from that of AZ71, 574, to 825 °C with the addition of 0.5 wt% Ca and 1 wt% Nd. The ignition temperature was further increased to 1114 °C when 3 wt% Ca was added. The Ca- and Nd-added AZ71 was isothermally maintained at a temperature of 500 °C in air for 12 h. The MgO–CaO–Nd2O3 formed on the surface to improve the thermal stability of the AZ71–xCa–yNd alloys. While both the tensile strength and ductility decreased with the Ca concentration in the alloy, an addition of 1 wt% Nd was found able to alleviate the degradation effects of Ca on the tensile strength and ductility at 170 °C. Both solid solution formation and precipitation strengthening contributed to the increase in toughness. AZ71 containing 0.5–2 wt% Ca and 1 wt% Nd provides the optimum combination of ignition resistance and mechanical properties.

Effects of natural weathering on the fire properties of intumescent fire‐retardant coatings

SummaryFire‐retardant coatings could be one option for providing enhanced protection to buildings during a wildfire, particularly when applied to combustible siding and in under‐eave areas. Limited studies have been conducted on their effectiveness but maintaining adequate performance after weathering has been questioned. This paper reports on a study evaluating the effect of natural weathering on the performance of intumescent‐type fire‐retardant coatings. The main concerns were (a) the reduction of ignition resistance of the coating after weathering and (b) the coating might contribute as a combustible fuel and assist the fire growth after weathering. This study evaluated the performance of 3 intumescent coatings that were exposed to natural weathering conditions for up to 12 months. A bench‐scale evaluation using a cone calorimeter was used to evaluate the performance of the coatings at 3 heat flux levels (30, 50, and 70 kW/m2). Our results showed that weathering exposure reduced the effectiveness of fire protection of intumescent coatings, but the weathered coatings did not act as additional fuels. Weathering orientation showed much less effect on the performance of intumescent coatings in comparison to other parameters. There was statistical evidence that weathering duration, heat flux level, and coating type affected the combustion properties.

Development and Evaluation of a Water-Based Flame Retardant Spray Coating for Cotton Fabrics.

In this Research Article, we report on the development of water-based flame retardant coating based on phospho-nitrogen combination for cotton fabrics. A one-step spray-on process was employed to coat the fabrics by taking advantage of the spontaneous reaction between para-phenylenediamine (PDA) and tetrakis(hydroxymethyl)phosphonium chloride (THPC) resulting in an instantaneous precipitation of poly[1,4-diaminophenylene-tris(dimethyl hydroxymethyl)phosphine] (PApP) on the fabric surface. The effectiveness of PApP in improving the flame retardant properties like ignition resistance and lateral flame spread were evaluated in accordance with ASTM D6413 and BS EN ISO 15025 flammability tests. Despite the early (thermal) decomposition onset for coated fabrics under both oxidative and pyrolytic conditions, remarkably, self-extinguishing behavior (<3 s) without any lateral flame spread was observed. Possible reaction scheme was also proposed to correlate flame retardant mechanism of the coated fabrics with the observations. Additional analysis via pyrolysis combustion flow calorimetry and vertical flame testing before and after washing showed that flame retardant efficiency did decrease with washing, but the overall performance was still promising.

Automation of a Distillation Column of Packed Bed for an Alcohol Solution using Arduino

This study demonstrates the use of Arduino to automate the operation of a distillation column binary ethanol - water as learning material used by students in the career of Chemical Engineering at the Escuela Superior Politecnica del Litoral. The main objective was to build an automated computer with the technology of arduino, in which thermocouples were used to offer students the convenience of taking temperature readings on a LCD display and in turn it allowed us to observe the level of the solution to control ignition resistance. So they were able to identify the processes that occur during the distillation unit operation automatically and manually in the Unit Operations Laboratory.

Lip Formation and Ejecta from LPSO-type Magnesium Alloy Plates in Hypervelocity Impact

Long period stacking ordered (LPSO) type magnesium alloys have the low density, excellent mechanical strength and ignition resistance. LPSO-type magnesium alloys have a great potential as structural materials of satellites. Lip formation and ejecta size were examined when spherical projectiles strikes thin plates made of LPSO-type magnesium alloy at hypervelocities of 5km/s. Witness plates were placed in front of and behind each target to determine the scattering area. After impact experiments, ejecta were collected from test chamber and lips near penetration hole was examined x-ray computed cosmography (CT) in detail. Results of LPSO-type magnesium alloy plates were compared with those of aluminum alloy (A6061-T6). Images of scattering ejecta taken by a high speed video camera were also discussed.

Ejecta From LPSO-Type Magnesium Alloy Targets in Hypervelocity Impact Experiments

Because long period stacking ordered (LPSO) type magnesium alloys have the low density, excellent mechanical strength and ignition resistance, LPSO-type magnesium alloys have a great potential as structural materials of satellites. Ejecta size and crater shape were examined when spherical projectiles struck targets made of LPSO-type magnesium alloy at hypervelocities of 2 km/s and 5 km/s. After impact experiments, crater surfaces and lips near craters were observed X-ray computed cosmography (CT) in detail. Ejecta collected from test chamber were measured. Results of LPSO-type magnesium alloy targets were compared with those of aluminum alloy (A6061-T6). Fracture behavior of LPSO-type magnesium alloy targets seemed to be brittle and many small ejecta from LPSO-type magnesium alloy were observed.

Transformadores de distribución que operan con aceite de origen vegetal como dieléctrico y refrigerante

Researches related with the use of Natural Ester Fluids as refrigerant of power transformers have been developed in other countries with successful results. In Colombia there is no a procedure to control the use of these esters in electrical apparatus, so the current implementations are regulated by NTC 1465 standards for mineral esters. This new proposal involves the composition and the most relevant properties (the ignition resistance, impact on the lifetime of the insulating papers and the impact on the environment), which makes the application of natural esters fluids advantageous not only to preserve the environment but also to get a better performance of power transformers.

Smoldering and Flame Resistant Textiles via Conformal Barrier Formation.

A durable and flexible silicone-based backcoating (halogen free) is applied to the backside of an otherwise smoldering-prone and flammable fabric. When exposed to fire, cyclic siloxanes (produced by thermal decomposition of the backcoating) diffuse through the fabric in the gas phase. The following oxidation of the cyclic siloxanes forms a highly conformal and thermally stable coating that fully embeds all individual fibers and shields them from heat and oxidation. As a result, the combustion of the fabric is prevented. This is a novel fire retardant mechanism that discloses a powerful approach towards textiles and multifunctional flexible materials with combined smoldering/flaming ignition resistance and fire-barrier properties.

Development of non-flammable high strength AZ91 + Ca alloys via liquid forging and extrusion

Non-flammable high strength magnesium alloys were developed from AZ91 alloy mainly for the weight reduction in industrial applications. Calcium of 2, 4 and 6wt.% was added and the ignition point was tested to study the flammability. Liquid forging and hot extrusion were applied to these alloys in order to enhance the mechanical properties. The microstructure, hardness and tensile properties were investigated to study the effects of calcium additions and different manufacturing processes. The results showed that calcium additions significantly improved the non-flammability, but mechanical properties of the gravity cast samples were degraded due to large amounts of Al2Ca at grain boundaries. After liquid forging and extrusion process, an increase of the mechanical properties was observed in the non-flammable magnesium alloys. The enhancement of properties was mainly contributed by the refined microstructure, redistribution of second phase and less porosity defects. Among all the tested alloys, AZ91+2% Ca prepared by liquid forging+extrusion demonstrated the optimal balance of high ignition point and excellent strength and ductility. 4% Ca addition further improves the ignition resistance and tensile strength of AZ91 alloy. The advantages of the manufacturing process combining liquid forging and hot extrusion were demonstrated to achieve improved mechanical properties for non-flammable magnesium alloys.

Ignition characteristics of semiconductor bridge based on lead styphnate and lead azide charges under capacitor discharge conditions

Eight different sizes of semiconductor bridges and three kinds of charges, namely normal-lead styphnate (N-LS), lead azide (LA) and the double stacked charge (N-LS/LA), were selected to study the ignition characteristics of semiconductor bridge igniters under capacitor discharge conditions. The Neyer D-optimal Method was utilized in the experiments to explore the critical ignition voltages of the igniters. The relationships among the ignition voltage, current, resistance, and ignition time as well as other parameters of these igniters were analyzed. The results obtained were as follows: 1) The critical ignition voltage is positively proportional with the bridge area for the igniters possessing identical charge and ignition mechanism. 2) The ignition time and critical ignition voltage are related to the charges. The relationship of ignition time and charge following the short to long ranking is LA, N-LS/LA, and N-LS, but the relationship of critical ignition voltage and charge follows the opposite ranking. 3) The electroexploding ignition mechanism brings about shorter ignition time than electrothermal ignition mechanism for the igniters with identical charge, but the electroexploding ignition mechanism is accompanied by higher critical ignition voltage than the other.

A quantitative optimisation model for a horizontal MEMS solid propellant thruster with experimental verification

This paper studies the effect of multiple geometric parameters of a micronozzle on a MEMS solid propellant thruster (MSPT) and establishes a quantitative optimisation model. Influences of the structural parameters of the micronozzle on performance are accurately calculated. The significance and contribution ratio of each parameter are evaluated by F distribution. Correspondingly, a horizontal MSPT is fabricated and tested to prove the optimisation model. In the implementation, a complete microigniter is formed by a single layer of Au, achieving an ultra-low ignition voltage of 2.1 V with an extremely low ignition resistance of 4 Ω.

Understanding the high temperature oxidation and ignition behaviour of two-phase Mg–Nd alloys and a comparison to single phase Mg–Nd

The oxidation kinetics and the mechanism of two-phase Mg–Nd alloys were investigated via isothermal heating experiments conducted in dry air at 500 °C for 12 h. The oxidation kinetic curves reveal improved oxidation resistance on neodymium (Nd)-containing alloys compared to pure Mg. A lower mass gain was detected at 2.5-%Nd than at 6-Nd%, which was related to the lower amount of intermetallic phase on the alloy surface. The intermetallic phase has a significant effect on the oxide growth stage. Nd2O3 formation on the intermetallic phases creates diffusion paths for oxygen to the metal/oxide interface, affecting both the oxidation kinetics and the oxidation resistance of the alloys. The formation of a Nd-depleted region at the subsurface due to extensive Nd oxidation at the oxide/intermetallic interface lowers the protective ability of the oxide scale. As increasing the Nd content of binary Mg–Nd alloys above 0.5 wt% shifts the alloys from single-phase region to two-phase region, it adversely affects the ignition resistance.

Investigation of Properties of CaO Added Wrought Mg-Zn-Y and Mg-Y-Zn Alloys

In this study, the effect of CaO as alloying element on Mg-Zn-Y and Mg-Y-Zn alloys were investigated to develop wrought magnesium alloys available for aeronautic components. The evaluation for the effect of CaO addition in these alloy systems was performed by the processing map development, the tensile test, and the ignition temperature measurement. The addition of CaO changed the hot workability and improved the ignition resistance of both Mg-Zn-Y and Mg-Y-Zn alloys. Although the mechanical properties of CaO added Mg-Zn-Y alloy were lower than those of Mg-Zn-Y alloy, the CaO addition in Mg-Y-Zn alloy enhanced the ductility of the alloy. The effect of metallic Ca addition in these alloy systems were investigated to be compared with the CaO addition.

Study of Ca and Ce Additions on Different Ignition Resistance Behavior of Magnesium Alloy

In order to develop ignition resistant magnesium alloy, Ca and Ce elements were selected alloying elements to fabricate Mg alloy. Different content of Ce (0,0.5,0.8,1.2,1.5wt%) and Ca (0, 0.6,0.8,1.0wt%) were added into pure magnesium to analyze their ignition-proof effect. The concentration of Ce and Ca elements on the melt surface was believed to be key factor for ignition resistance, which caused the change of interfacial tensions. It was indicated that the ignition resistance could be improved with increase of Ce and Ca addition. This could be attributed to a protective surface oxide owing to the diffuse of Ce and Ca to surface.

Effect of Nd and Dy Addition on AZ91D Ignition Temperature and Microhardness

Magnesium alloys are very active and readily ignite during heating and melting. In this study, the ignition-proof property of AZ91D with Nd and Dy addition was discussed, and the effects of these ignition-proof elements on the microstructure and microhardness of AZ91D investigated. The results show that the ignition-proof performance of magnesium alloy is improved obviously. The ignition resistance is attributed to the compact oxide films, which consist of MgO, Al2O3, Nd2O3, Dy2O3. When Dy content increased beyond 0.5%, the change tendency of ignition point of the alloy follows the shape of “v” curve, and the ignition point increased with Nd addition. The optimum composition of the newly developed magnesium alloy is AZ91D-3Nd-0.5Dy with the ignition point about 60K higher than AZ91D. And also AZ91D-3Nd-0.5Dy has fine microstructure and higher microhardness.

Effect of Re Addition on the Ignition Resistance of Pure Magnesium

This paper focus on the effect of rare earth elements addition on the oxidation resistance of pure magnesium. The results show that the ignition points of the Mg-RE alloys vary like “V” along with the increase of the rare earth elements. When the content of Y reaches 10wt%, the ignition point of magnesium alloy is 890K, about 40K higher than the ignition point of pure magnesium. After the addition of rare earth elements, dense oxide film forms on the surface of Mg-RE alloys. The outer oxidation film mainly consists of rare earth oxide.