Ceramifiable Cable Layer for Fire Resistance and Mechanical Strength
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Solution Overview
Problem
Fire resistant cables with ceramifiable compositions often form non-uniform and cracked ceramic layers when exposed to elevated temperatures, and lack mechanical strength to withstand fire extinguishing stresses like water jets.
Innovation Solution
A fire resistant cable with a ceramifiable composition comprising an ethylene/vinyl acetate copolymer, at least 25 wt% silica, a stabilizing agent (MgO, CaO, PbO, or B2O3), and a fluxing agent (alkaline metal oxides) along with a minor amount of flame-retardant hydroxide, forming a coherent ceramic layer with enhanced mechanical strength and fire resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ceramifiable compositions are used in fire resistant cables, then fire resistance is improved, but the ceramic layer becomes non-uniform and cracked
Solution Approach 1:
The patent modifies the chemical composition parameters of the ceramifiable layer by incorporating specific ratios of glass-forming oxides (40-70 wt%), stabilizing oxides (10-30 wt%), and fluxing oxides (5-20 wt%). This parameter optimization ensures uniform ceramic transformation during fire exposure while maintaining structural integrity and preventing cracking.
Solution Approach 2:
The invention creates a composite ceramifiable material combining multiple oxide components with complementary functions: glass-forming oxides for ceramic matrix formation, stabilizing oxides for structural reinforcement, and fluxing oxides for low-temperature melting and uniform distribution. This composite approach achieves both fire resistance and layer uniformity.
2Reliability
If ceramifiable compositions are used to form protective layers, then fire resistance is improved, but mechanical strength against water jets deteriorates
Solution Approach 1:
The patent optimizes the chemical composition parameters to balance fire resistance and mechanical strength. Specifically, stabilizing oxides (10-30 wt%) provide structural reinforcement for water jet resistance, while glass-forming oxides (40-70 wt%) ensure ceramic formation at fire temperatures. This parameter balance achieves both required properties simultaneously.
Solution Approach 2:
The ceramifiable layer is designed as a multi-component composite where stabilizing oxides contribute to mechanical strength and water jet resistance, while glass-forming oxides provide fire protection through ceramic transformation. The synergistic combination of these composite materials resolves the contradiction between fire resistance and mechanical strength.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The cable maintains circuit integrity and withstands mechanical stresses, forming a ceramic layer that is substantially free from cracks and swellings, allowing it to operate effectively during fires and withstand water jet impacts.
Implementation Method 1
a fire resistant cable with a ceramifiable composition... forming a coherent ceramic layer... substantially free from cracks and swellings
Implementation Method 2
a fluxing agent (alkaline metal oxides)... forming a coherent ceramic layer with enhanced mechanical strength and fire resistance
Implementation Method 3
a stabilizing agent (MgO, CaO, PbO, or B2O3)... forming a coherent ceramic layer that is substantially free from cracks and swellings
Data Source
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AI summary
A fire resistant cable comprising: at least one conducting element; at least one layer, surrounding said conducting element, made of a ceramifiable composition comprising: a polymeric material comprising an ethylene/vinyl acetate copolymer as main polymer; at least 25 wt% of silica; a fluxing agent selected from alkaline metal oxides or precursors thereof; a stabilizing agent comprising at least one of MgO, CaO, PbO, B203, or a precursor thereof; from 0.1 wt% to 5 wt% of a hydroxide selected from magnesium hydroxide, aluminium hydroxide and mixtures thereof; the above percentages being expressed with respect to the weight of the ceramifiable composition. Upon exposure to elevated temperatures such as those encountered in case of fire, the ceramifiable composition is transformed into a ceramic material capable of protecting the conducting element from fire and mechanical stresses. The fire resistant cable of the present invention can continue operating under fire conditions for a certain period of time.