Erosion of Propellants

Burning, Erosive(in Propellants)(Erosive Effect of Gas Flow or Erosion of Propellants). Mansell (Ref 1) was one of the first to observe that the rate of burning inside tubular proplnts was faster than that on the outside. A similar phenomenon was observed later by Muraour(Ref 2). No importance was attached to this phenomenon until it was observed also(but on a larger scale) in rocket motors during and after WWII(Ref 11)... 

This type of damage is dealt with comprehensively in Section 8.8. It can be particularly severe in seawater giving rise to cavitation corrosion or cavitation erosion mechanisms, and hence can be a considerable problem in marine and offshore engineering. Components that may suffer in this way include the suction faces of propellers, the suction areas of pump impellers and casings, diffusers, shaft brackets, rudders and diesel-engine cylinder liners. There is also evidence that cavitation conditions can develop in seawater, drilling mud and produced oil/gas waterlines with turbulent high rates of flow. 

Uses. In ultraviolet stabilizers and smoke depressants for polymers to increase the burn rate of rocket propellants to prevent erosion of space capsule shields to improve the viscosity of lubricants to catalyze polymerization reactions to catalyze combustion some derivatives used as hematinic agents... 

Burning (Combustion) Erosive in Propellants is briefly discussed in Vol 2 of Encycl, p B357 [There is an error on p B357-R, 4th line from the top. It should be proplnts), instead of expins),]... 

A. Jaumotte, "Remarks on the Burning Mechanism and Erosive Burning of Ammonium Perchlorate Propellants , Ibid, pp 689-93 G2) G.K. Adams et al, "Combustion of Propellants Based on Ammonium Perchlorate , Ibid, p 693-705 Hj) J.Hershkowitz, F. Schwartz J.V.R. Kaufman, "Combustion of Loose Granular Mixtures of Potassium Perchlorate and Aluminum , Ibid, pp 720-27 H2) L.A. Dickinson et al, "Erosive Burning of Polyurethane Propellants in Rocket Engines , Ibid, pp 754-59 H ) S. Kumagai... 

The same theory was described in 1934 by WShler 8c Roth (Ref 2). Roth referred in his description to the surface erosion in propellant burning as "DasPinmbertsche Gesetz von 1839", citing as a reference Vol 2, p 120 of "Lehrbuch der Ballistik" by C. Cranz (1926)... 

These propellants also contain nitroglycerine (NG) in addition to NC and the proportion of NG depends on the performance desired from double-base (DB) propellants. DB propellants are more energetic than SB propellants and have Q value between 3300 and 5200Jg 1. There are two disadvantages in the use of DB propellants higher erosion of the gun-barrel as a result of higher flame temperatures and presence of a muzzle flash which discloses the location of the gun. DB propellants are used in pistols, mortars, rockets and missiles. 

In calculating the life of a gun barrel, it was considered in Germany to relate to the "effective calorific value , more than to the values obed in a calorific bomh (See also under " Energy Content of a Propellant Charge" and under "Erosion of the Bore")... 

Experimental procedure for detn of erosive burning of propellants used by Vieille is described in Ref 1, p 195 and briefly by Davis in Ref 26, p 294 and also in this item under Historical . More recent determination was done by Andreev Belyaev as described in Ref 45 (See also Refs 16, 27, 28, 29, 30, 35, 36,... 

One of the reasons (or increased erosion is the formation of soft steel on the surface of the bore. This softening is caused by increased percentage of carbon, which.comes from C of propelling gases when they attack the surface of the bore while it is at temp of 300 500°(Ref 43, p 155)... 

Erosion is increased and life of a gun is decreased with increase of propelling charge and increase in caliber of gun... 

CA 48, 11061(1954) (Erosive burning of some composite solid propellants) 37) H.H. Abram, T. Williams K.F. Allen, Examination of Six QF 17-pr Gun Barrels Used in Ballistic and Erosion Trials of Propellants of Various Compositions and Flame Temperatures , Armament Research Establishment Metallurgy Report No 8/54, Woolwich,... 

ACT 5 (Ardeer Cordite Tubular No 5)- A batch No 320B delivered in 1938 for the Brazilian Navy had to meet the following specification requirements NC(N= 11.8 +0.2) 65.0 +1, NG 29.0 + 1 and centralite 6.0 +0.5% Graphite could be added to the extent of 0. 2% and max moist content of ACT 5 was 1% Ref Adm Alvaro-Alberto, Rio de Janeiro private communication Oct 14, 1958 ACT 5, Erosion of. The erosive action of ACT 5 as well as of some other propellants was investigated in Brazil by Admiral Alvaro-Alberto (Ref 2) from the point of view of Vieille s erosion theory (Ref 1). This theory was modified using some later data of Muraour and of other investigators. A brief resume of Alvaro-Alberto s work on erosive action of propellants is given in CA 40, 2629-30(1946)... 

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