Mikrotomschnitt- Technik and Mineraluntersuchungen 



333 



further centrifuging operations by ether until finally 

 a dispersion of the debris in ether is obtained. One 

 drop of this dispersion is then used for examination. 



For a statistical determination of particle size in 

 wear debris the debris from short duration tests was 

 centrifuged on to a formvar film supported on a 

 microscope grid which in turn, supported by a plug, 

 formed the end of the centrifuge tube. By this 

 method all debris from the test was collected on the 

 formvar covered grid. 



The debris taken from a steel surface although 

 generally irregular in shape, often contains rod like 

 particles the presence of which is believed to indicate 

 that some of the debris may be produced by fragmen- 

 tation of the pearl ite structure. 



Discussion and conclusions. — The micrographs ob- 

 tained show that the electron microscope can, with 

 the use of a formvar replica technique, reveal small 

 scale features of interest in the study of wear and 

 can yield experimental evidence for postulated theo- 

 ries of the mechanism of wear. 



With very hard steel there is little plastic deforma- 

 tion, and overstressing of the surface appears to 

 initiate damage by fine cracks and the displacement 

 of material by microscopic adhesion of the contacting 

 asperities (fig. 2), possibly in the manner suggested 

 by Bowden and Tabor (2). With carbon steel in the 

 annealed or softened state considerable plastic rough- 

 ening of the contacting surface is evident (fig. I), 

 resulting in a pattern of ridges and grooves with 

 mating surfaces probably conforming exactly, as 

 suggested by Ming- Feng (6). 



Although named freiling corrosion, presumably 

 owing to the accumulation of oxidised debris, the 

 initiation of surface damage appears to be similar to 

 the onset of wear of rubbing surfaces, fine debris 

 produced by the initial damage being the start of 

 cumulative abrasive action. 



The authors wish to acknowledge the assistance they 

 have received from their colleagues in the Mechanical 

 I ngincering Research Laboratory in providing, for elec- 

 tron microscope study, specimens which have been sub- 

 jected to various forms of wear test. In particular, Mr. 

 A. A. Milne has provided guidance regarding the test 

 conditions and the bearing of the results on current 

 knowledge of friction and wear. I he work described has 

 been carried out as part of the programme of the Lubri- 

 cation and Wear Division of the Mechanical Lngineering 

 Research Laboratory and the paper is published by 

 permission of tlie Director. 



References 



1. Barwell, F. T. et al.. Proceedings Fourth World Petro- 



leum Congress. Sect. VI C Preprint 3. 1955. Brit. 

 Patent No. 732447. 



2. BowDHN, F. p. and Tabor, D., The Friction of Lubrica- 



tion and Solids. University Press, 1950. 



3. Bradley, D. £., J. Inst. Metals 83, 35 (1955). 



4. Halliday, J. S., Proc. Inst. Mecli. Eni;rs. 169, No. 38 



(1955). 



5. Menter, J. W., J. Inst. Metals 81, 163 (1952). 



6. Ming-Feng, I., J. Appl. Pins. 23, 1011 (1952). 



7. MooRF, A. J. W., Mctallingia 38, No. 224 (1948). 



8. Wright, K. H. R., Proc. Inst. Mech. F.ni^rs. (B) IB, 



No. 11, 566-574 (1952-53). 



Anwendungen (der Mikrotomschnitt-Technik 

 auf elektronenmikroskopische Minerakintersuchungen 



G. Pfefferkorn, H. Themann und H. Urban 



Medizinische Elektionenmikroskopie, Universitcit Miiiisterj Westf. 



JjLSHER fiihrte man elektronenmikroskopische Mine- 

 raluntersuchungen an kleinen Einkristallen bzw. 

 Aggregaten im Durchstrahlungsverfahren durch, 

 wiihrend Kristalloberfiachen mit verschiedenen Ab- 

 druckverfahren studiert wurden. Es fehlte bislang 

 die Moglichkeit, Mineralaggregatc in Querschnitten 

 zur Feststellung der dreidimensionalen Textur zu 

 untersuchen. 



Aus diesem Grunde haben wir versucht, das bei 

 biologischen Objekten gebriiuchliche Verfahren der 

 Einbettung und Schnitt-Technik auf kristalline Kor- 

 per anzuwenden. 



Es zeigte sich, daB porose Aggregate, in deren 

 Hohlraume das Einbettungsmedium eindringen 

 kann, nach der Polymerisation schon mit Glasmes- 

 sern schneidbar sind. Noch giinstigere Erfolge erziel- 



ten wir mit dem Diamantmesser cines Ultra-Mikro- 

 toms nach Moran der Firma Leitz. Die Kristallag- 

 gregate wurden vor der Einbettung zur Besciligung 

 von Feuchtigkeitsspuren im Vakuumtrockenschrank 

 erwarmt oder mit absolutem Alkohol \orbehandelt. 



Die bisherigen Untersuchungen fiihrten zu folgen- 

 dcn Ergebnissen: 



Glaukonit, ein charakteristisch griines kalium- 

 und magnesiumfiihrendes Eisenaluminiumsilikat mit 

 Glimmcrstruktur, liegt in der Natur in gerundeten, 

 hiiufig eiformigen Kornern vor. die, wie die licht- 

 mikroskopische Untersuchung im Gesteinsdiinn- 

 schlifT zeigt, aus polykristallinen Aggregaten beste- 

 hen. Mit der Schnitt-Technik kann man jet/t den 

 Aufbau einzelner Korner genauer studieren. Schon 

 lichtmikroskopisch zeigen die Schnittc in verschic- 



