W. J. Tomlinson

Erosion and corrosion of cast iron under cavitation conditions

Abstract Cavitation erosion of cast iron depends on both the microstructure of the cast iron and on the nature of the corrosive environment. The cavitation erosion of cast iron is concisely reviewed with an emphasis on the effects of the microstructure and corrosion. Some recent published work is then examined and discussed in terms of the erosion, corrosion and corrosion-induced erosion of the cavitation damage. In a range of cast irons in various metallurgical conditions, it is seen that typically less than a fraction 0.05 of the damage arises from electrochemical corrosion and that typically a fraction 0.70–0.85 of the damage arises from corrosion-induced erosion. Exceptions to these cases, and the mechanism of damage, are discussed.

Cavitation erosion of grey cast irons containing 0.2 and 1.0% phosphorous in corrosive waters

Abstract The effect of 0.2 and 1.0% P in a sand cast flake graphite grey iron on the cavitation erosion behaviour in distilled, NaCl, and NaCl/inhibitor waters, has been investigated. Techniques used include an ultrasonic vibratory apparatus at 50°C and 15 μm amplitude, electrochemical polarization, profilometry, and microscopy. Salt in the water increased the electrochemical corrosion rate, the erosion rate, the number of pits/cracks in the surface, the roughness of the surface, and reduced the nominal incubation time. For the 0.2% P iron in 3% salt water the nominal incubation time was reduced by 0.2 times, the steady-state erosion rate increased by 7.0 times and 90% of the increase was due to corrosion-induced erosion. The presence of a continuous brittle phosphide network in the 1.0% P iron had a negligible effect on the erosion rate but reduced the incubation time by a factor of 0.3. The inhibitor eliminated completely the effects of corrosion up to a salt concentration of 0.25%. The processes and mechanisms are discussed.

Cavitation erosion of pure iron in distilled water containing chloride and chromates

Abstract The erosion of pure iron in distilled, 1% NaCl, and 1% NaCl/chromate waters has been investigated using a vibratory cavitation apparatus and the damage examined using profilometry and metallographic techniques. The maximum erosion rate is associated with the formation of a deeply corrugated surface and transcrystalline cracks up to 50 μm deep. Salt in the water decreased only slightly the nominal incubation period, but increased by nearly 40% the maximum erosion rate and etched the eroding surface. Addition of 2000 ppm chromate eliminated the effects of chloride.

Strength of surface-modified calcite/nylon 6 composites

Summarizing the present work on the tensile properties of nylon 6 and nylon 6 composites containing 10, 20, 30, 40 and 50 wt% calcium carbonate particles, uncoated or coated with either amino-caproic acid or steric acid, it was seen that the strength was progressively increased, stayed much the same and was progressively decreased by an increase in the amount of uncoated, amino-caproic acid-coated and steric acid-coated calcite, respectively. The strength of the composites was analysed using a model that allowed an interpretation of the filler-matrix interaction, and the results of this were consistent with the possible chemical bonding at the interface

Early stages of wear of copper steel, and electroless nickel against

Abstract The early stages of wear of copper, mild steel, an alloy steel, and electroless nickel in the as-deposited and heat-treated conditions, with a load of 50 g against a dry nitrided steel wheel with a surface speed of 0.28 m s −1 , were measured using a Talysurf and a precision relocation technique, and the worn surface was examined using scanning electron microscopy. Wear occurred mainly by abrasion. Extensive ploughing with cooper resulted in metal removal and redeposition on the surface. Rapid and severe removal of patches of material occurred witb mild steel, and fragments of the metal were redeposited on the surface. As-plated electroless nickel formed many small cracks in the wear tracks. These were absent in the heat-treated coating when surface damage occurred by brittle fracture of the Ni 3 P. Profilometry results taken during the wear tests were analysed and related to the microscopical results and the wear processes.

Fibre coatings and the mechanical properties of carbon fibre/nylon 6 composites

We investigated the effects of seven kinds of coating on the mechanical properties of carbon fibre/nylon 6 composites

Substrate roughness, cold work and the oxidation of pure iron at 200 to 600° C

To a large extent the direction of the work was determined by the problems experienced during ageing specimens for wear testing, and the need for information on the formation of oxide films in the temperature range 200 to 400°C

Affect of deposition in an ultrasonic field on the corrosion of electroless nickel coatings

The present work investigated the effect of deposition in an ultrasonic field on the corrosion of electroless nickel coatings

Silicon steels hot-dip galvanized with zinc-nickel alloys

0.002 0.002 0.005 0.001 0.001 0.002 <0.01 0.002 0.003 0.012 0.048 0.014 0.004 0.25 0.020 0.004 0.020 0.011 0.059 0.193 0.006 0.008 0.44 0.010 0.002 0.010 0.010 0.172 0.173 0.001 0.009 0.42 0.020 0.003 0.020 0.023 0.260 0.05 0.001 0.009 1.41 0.020 0.005 0.02 0.020 0.340 0.096 0.011 0.092 0.37 0.030 0.009 0.370 0.880 0.450 0.160 0.005 0.017 1.34 0.02 <0.005 0.005 0.020

Effect of waviness on the wear behaviour of 080 M40 (EN8) and 817 M40 (EN24A) steels

Abstract The effect of waviness was investigated on the wear performance of 080 M40 and 817 M40 steels machined by the turning and surface grinding processes for a sliding wear situation. The wear was measured with a precision relocation technique using a Talysurf 4 and the frictional coefficient force was monitored using a load cell. The worn surface was examined using scanning electron microscopy. For both types of steel, contact was at the wave crests. The crests were progressively truncated and work-hardened during the wear cycle. Generally, friction increased during running-in and stabilized on complete removal of the waves. For dry wear regimes high interfacial temperatures were set up at the wave crests. Consequently, the pin material oxidized and the friction and wear behaviour of the surface altered. On running-in the turned 817 M40 specimens showed large scale redeposition due to adhesive wear at the wave crests whilst the valleys were relatively smooth due to an abrasive process. A white layer of untempered martensite was produced at the surface of the ground 817 M40 specimens. This hard layer initially resisted abrasion and reduced friction.