Explosives-Intro_to

Historical Development of Explosives

  • 220 BC: Chinese develop black powder.

  • 1044 AD: Chinese publish black powder formula for military use.

  • 1244: Roger Bacon publishes the formula in England, sharing knowledge from Chinese sources.

Chemical Composition of Black Powder

  • Components:

    • Charcoal: 19.031% (mass)

    • Sulfur: 8.431% (mass)

    • Potassium Nitrate (KNO3): 72.537% (mass)

Advancements in Explosives Technology

  • 1280: Chinese use the first cannon to propel metal.

  • 1327: Europeans adopt explosives for firing bombs.

  • 1588: Development of the first hollow shells filled with black powder.

  • 1627: Use of black powder in Hungary for mining purposes.

  • 1696: Switzerland applies black powder for road construction.

  • 1784: Shrapnel invents metal shells that can explosively throw metal.

  • 1804: DuPont begins the first commercial manufacturing of explosives in the U.S.

  • 1831: Bickford invents the safety fuse.

  • 1838-1846: Discovery of nitrocellulose by Pelouze.

Notable Discoveries in Explosives

  • 1847: Discovery of nitroglycerin by Sobrero.

  • 1855: Alfred Nobel invents dynamite.

  • 1864: Nobel builds the first nitroglycerin plant using black powder for initiation.

  • 1867: Swedish chemists patent an ammonium nitrate (AN) explosive.

  • 1867: Nobel invents mercury fulminate as a blasting cap to initiate dynamite.

  • 1885: Nobel purchases the AN patent from Swedish chemists and adds it to dynamite.

  • 1887: Nobel invents smokeless powders.

Milestones in Explosives Manufacturing

  • 1891: First manufacturing of Trinitrotoluene (TNT).

  • 1914: TNT becomes the standard military explosive used.

  • 1917: Maximum usage of black powder during WWI.

  • 1955: Development of ANFO (Ammonium Nitrate Fuel Oil).

  • 1960s: ANFO begins to replace dynamite.

  • Current Trends: Plastics, remote-controlled explosives, dirty bombs, biological explosives, RDX, detonation cords, emulsions, slurry explosives, etc.

Classifications of Explosives

Types of Explosives

  • Low Explosives: Hazardous materials that combust slowly.

  • High Explosives: Fast-reacting materials that detonate under specific conditions.

Modes of Combustion

  • Ordinary: Slow combustion

  • Explosion: Rapid combustion

  • Detonation: Instantaneous combustion

Nature and Function of Explosives

  • Definition: Material capable of producing an explosion without external oxygen.

  • Characteristics:

    • Capable of undergoing rapid exothermic reactions or decomposition.

    • Must either detonate or deflagrate rapidly.

Explosive Dynamics

Detonation Process

  • Detonation involves a shock wave that propagates through the explosive material at supersonic speeds, converting solid material into rapidly expanding gases.

Primary and Secondary Explosives

  • Primary Explosives: Sensitive explosives that initiate a larger explosion.

  • Secondary Explosives: Require a primary explosive to detonate.

Explosive Effects

Three Major Effects of Explosions

  1. Blast Pressure: High-pressure wave generated at the moment of detonation.

  2. Fragmentation: Shrapnel and other debris ejected outward.

  3. Thermal Effects: Heat produced that can ignite materials nearby, causing incendiary effects.

Power of the Blast

  • Positive Pressure Phase: High-pressure wave that expands outward from the explosion point.

  • Negative Pressure Phase: Vacuum created post-explosion, resulting in air rushing back into the void.

Types of Explosions

Mechanical Explosions

  • Involves pressure build-up leading to structural failure in vessels (e.g., steam boilers).

Chemical Explosions

  • Rapid conversion of substances resulting in heat and gas production, typical of most manufactured explosives.

Nuclear Explosions

  • Induced via fission or fusion reactions leading to massive energy release.

Combustion Requirements

  • Necessary Components:

    • Combustible material

    • Supporter of combustion (usually oxygen)

    • Heat to achieve ignition

Combustion and Explosion Dynamics

  • Effective supporter of combustion: Oxygen (Air contains about 21% oxygen).

  • An explosion is a rapid form of ordinary combustion, with the key difference being the speed of the reaction.