Ignition by friction

Other early match-like devices were based on the property of various combustible substances mixed with potassium chlorate to ignite when moistened with strong acid. More important was the property of chlorates to form mixtures with combustibles of low ignition point which were ignited by friction (John Walker, 1827). However, such matches containing essentially potassium chlorate, antimony sulfide, and later sulfur (lucifers), mbbed within a fold of glass powder-coated paper, were hard to initiate and unreHable. 

Chemical Reactivity - Reactivity with Water. Reacts with liquid water or atmospheric moisture to liberate toxic hydrogen sulfide gas Reactivity with Common Materials No reaction Stability During Transport Can be ignited by friction Neutralizing Agents for Acids and Caustics Not pertinent Polymerization Not pertinent Inhibitor of Polymerization Not pertinent. 

In a French factory streaks of Picric Acid had been formed alongside a narrow gauge railway. As the soil beneath was calcareous, calcium picrate formed which, having dried up in the summer, was ignited by friction or a blow, spreading flames all over those parts of the factory marked with calcium picrate streaks ... 

Although the massive metal is relatively inert, when powdered it becomes very reactive. The dry powder may react explosively at elevated temperatures with nitrogen, phosphorus, oxygen, sulfur and other non-metals. The halogens react similarly, and in contact with hot cone, nitric acid and other oxidants it may explode (often after a delay with nitric acid). The powder is pyrophoric and readily ignitable by friction, heat or static sparks, and if dry bums fiercely. Presence of... 

The general reactivity of the sulfide depends markedly on the physical form, and differences of a factor of 10 may be involved. It is ignitable by friction, sparks or flames, and ignites in dry air if heated close to the m.p., 275 -280°C. The dust (200 mesh) forms explosive mixtures in air above a concentration of 0.5% w/v [1], and maximum explosion pressures of 4.35 bar, with maximum rate of rise exceeding 680 bar/s have been determined [2], The dust can acquire sufficient static electricity from movement for ignition to occur [3],... 

Fig. 11.21 shows the results of TG and DTA measurements on mixtures of AP particles and catalysts. The endothermic peak observed at 513 K is caused by the crystal structure transformation of AP from orthorhombic to cubic. A two-stage exothermic decomposition occurs in the range 573-720 K. The decomposition of the AP is seen to be drastically accelerated by the addition of catocene. The exothermic peak accompanied by mass loss occurs before the AP crystal transformation. Although the AP is sensitized by the addition of carborane, no effect is seen on the AP decomposition. The results indicate that carborane acts as a fuel component in the gas phase but does not catalyze the decomposition of AP. Thus, the critical friction energy is lowered due to the increased reaction rate in the gas phase. The results imply that the initiation of ignition by friction is caused by the ignition of the gaseous products of the AP pyrolants.PI... 

Hargreaves patented a device in which the fuse was ignited by friction (Ref 3)... 

Friction Compositions for Friction Detonators Friction Firing Devices and Friction Igniters or Primers. These are powders which are easily ignited by friction. Some of the simplest mixtures are K chlorate with sugar or with antimony sulfide. Davis (Ref 1, p 453) gives table listing three compns which have been widely used in friction primers for artillety, separate-loaded ammunition... 

To modify the sensitiveness of the mixt to ignition by friction or blows... 

Chemical Candles.) A device(now obsolete) consisting of a thin metal container filled with a chem agent and provided with a match -head which could be ignited by friction or electrically. These candles were used both for screening and harassing effects Ref Hayes(1938), 623... 

Ignition Caused by Rubbing Friction. Solids can be ignited by frictional sources when rubbed against each other or against another... 

Compared to other reactive chemicals, ignitable reactive chemicals are extremely hazardous. They ignite by friction or mechanical impact, or by contacting sparks due to static electricity, or by hot surfaces or hot objects, or fire. Often their ignition leads to... 

Pieces cut from a sheet of detonator paper for games were kept in a box, and when they were taken out they ignited and and injured a person. Explosive pieces that ignited upon being dropped were thought to have been ignited by friction. 

Matches without Sulphur, which can be ignited by friction on any surface and do not absorb moisture from the air, are prepared by dipping the matches into a hot solution of any kind of fat, and using the following inflammable compound Seven parts of phosphorus, 7 of gum-Arabic, 40 or lead nitrate, 5 of pulverized glass, and 10 of water. 

These strips are theu coated with a varnish to protect them from moisture and to prevent their ignition by friction during transportation, etc. 

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