Friction tests

Velocity, m /min Wear factor Dynamic K X 10-", 1/Pa " coefficient of friction Test duration, h... 

Fig. 5. Wall friction test (a) apparatus for measurement, and (b) results, where is the wall friction angle.

Modtilus Measurements Another SCC test technique is the use of changes of modulus as a measure of the damping capacity of a metal. It is known that a sample of a given test material containing cracks will have a lower effec tive modulus than does a sample of identical material free of cracks. The technique provides a rapid and reliable evaluation of the susceptibility of a sample material to SCC in a specific environment. The so-called internal friction test concept can also be used to detect and probe nucleation and progress of cracking and the mechanisms controlling it. 

Gain in wt in 200 hours Pendulum Friction Test, Steel Shoe. 0.04... 

The friction coefficient can be easily obtained in traditional tribological test. However, in the microscale friction test, the relative moving status of the tip is greatly affected by the surface morphology, and the friction coefficient should be obtained by theoretical analysis according to the experimental condition. A model shown in Fig. 4 is set up to analyze the relative moving status of the tip. 

For PTFE film and PTFE/Si3N4 multilayers, through the observation of the surface morphology after the micro wear test, it is found that there is obvious worn mark and projection in the edge of worn mark when the load is above 70 nN (Figs. 11 and 12). As to the Si3N4 film, there is no worn mark observed even when the maximum load is used in the micro friction test. 

The L-B film studied consists of two-layer organic molecules. The first layer of the L-B film is adsorbed on silicon substrate by the polarization terminals of the molecules. During the micro friction test, the probe contacted with the polarization terminal of the second layer. As a result, there was a special attractive force between the polarization terminal of the second layer and the probe. Therefore, the L-B film does not have the function of reducing friction force under the current experimental condition. 

The same nano scratch tester was used to carry out the friction tests. The Rockwell diamond tip (radius 2 /u.m) was used to draw at a constant speed 3 mm/min across the sample surface under a constant load of 20 mN for which no scratches occurred for all the samples. Feedback circuitry in the tester ensures the applied load is kept constant over the sample surface. The sliding distance is 3 mm. The friction coefficient is defined normally as the ratio of the friction force and the applied load. 

Fig. 36—Friction test of Sample 2, F is the friction force, Pd is the penetration depth, Nm is the measure normal load (20 mN) during the friction test.

The constant applied load is only 20 mN so there were no crack formations occurring during the friction tests of all the samples though there is penetration depth on the sample surface. The friction coefficient reflects the surface feature of H DLC samples. Figure 37 shows the friction coefficient of all samples. Sample 2 has the lowest friction coefficient compared to other samples which have the friction coefficient in a range of 0.049-0.065. 

Fig. 6.6. Friction tests, (a) Liquid explosives, (b) Solid explosives.

A common hazard in the handling of explosives is for them to be subjected to the effects of a blow which is to some extent at a glancing angle. This corresponds neither to pure impact, nor to pure friction. A corresponding simple and useful test for the safety of an explosive during handling is the torpedo friction test illustrated in Fig. 6.8. In this, a torpedo... 

Torpedo friction test. A test of sensitiveness to impact and friction (see p. 70). 

Friction Sensitivity (Roto-Friction Test Device]... 

Determination of friction sensitivity is applicable to solids, pastes, and gel-type substances. To determine the friction sensitivity, a thin sample is placed under a load between two roughened surfaces, and the surfaces are then rubbed together in a controlled manner. The load can be varied. Results from this action, such as smoke, cracking, or discoloration, are observed. Examples of apparatus of this type are the BAM friction apparatus, shown in Figure 2.30, the rotary friction test, and the ABL friction test. 

Lead Block and Copper Cylinder Compression Tests (113-15) Ballistic Pendulum Test (115-16) Fragmentation Test (Geschoss-Splitter Probe (118) Impact Test by Falling Weight (118-20) Deflagration Point (Verpuf-fungstemperatur) (120) Friction Test (120-21) Rifle Bullet Test (Beschussprobe) (121)... 

Power by Trauzl Test (142-45), by Compression Test (Ensayo por recalcado) (145-46) and by Ballistic. Pendulum (146) Fragmentation Test (148-49) Impact Test (Ensayo con un pilon) (150-53) Temperature of Deflagration (153) Friction Test (Ensayo de rozamiento) (153-54) Rifle Bullet Test (Ensayo de impacto) (154)... 

The minimum temperature developed by hot spots for initiation can be determined by compression of a known volume of air surrounding the expl. This type of test, described in Ref lp, p 60, gives results, shown in Table IX of Ref 22, p 162, which are in fairly close agreement with the friction test... 

Friction Test, steel shoe Detonates Partially deton... 

Friction Test, fiber shoe Unaffected Unaffected... 

Friction Test. A small sample of explosive rubbed in an unglazed porcelain mortar should not show greater sensitivity than PA at room temp... 

W() Kirk Othmer, Vol 8(1952), pp 654-57 (Section on Testing Exolosives which includes Impact Tests, Explosion Temperature Tests, Sensitivity to Initiation, Pendulum Friction Test, Rifle Bullet Test, Sand Test, Rate of Detonation Determination, Ballistic Pendulum Test, Trauzl Lead Block Test,... 

A small amt of the expl was spread on a large stone table and then struck a glancing blow with a mallet made either of rawhide or beech wood. The expl was thus subjected to the combined effect of shock and friction. If the sample exploded, the test was repeated by hitting the expl a glancing blow with a broomstick held at an angle of 60° against the table, taking care that the movement of the stick is in the direction of its axis. If an expin were obtd, the test was repeated on a hard wooden table and finally on a soft wooden one. If an expl, other than those used for caps, detonators, etc exploded, even partly on soft wood, it was considered to be too sensitive for use (Compare with Torpedo Friction Test, described as quantitative test i, Fi g F22)... 

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