Effect of temperature on passive film formation of UNS N08031 Cr–Ni alloy in phosphoric acid contaminated with different aggressive anions

2013 ◽  
Vol 111 ◽  
pp. 552-561 ◽  
Author(s):  
C. Escrivà-Cerdán ◽  
E. Blasco-Tamarit ◽  
D.M. García-García ◽  
J. García-Antón ◽  
R. Akid ◽  
...  
Keyword(s):  
Phosphoric Acid ◽  
Passive Film ◽  
Film Formation ◽  
Effect Of Temperature ◽  
Ni Alloy

Mechanical Properties of ZDTP Tribofilms Measured by Nanoindentation: Strain Rate and Temperature Effects

2008 ◽  
Author(s):  
S. Bec ◽  
K. Demmou ◽  
J.-L. Loubet
Keyword(s):  
Mechanical Properties ◽  
Elastic Modulus ◽  
Strain Rate ◽  
Film Formation ◽  
Point Of View ◽  
Effect Of Temperature ◽  
Zinc Dialkyldithiophosphate ◽  
Wear Rates ◽  
Versus Strain ◽  
Antiwear Action

This study aims to contribute to better understand the antiwear action of zinc dialkyldithiophosphate (ZDTP) additives used in car engine lubrication. The antiwear action of ZDTP is associated to the formation of a protective tribofilm onto the rubbing surface. On a mechanical point of view, the efficiency of ZDTP tribofilms results from equilibrium between film formation and wear rates, associated with appropriate rheological properties. In this work, the mechanical properties of a ZDTP tribofilm have been measured by nanoindentation in different test conditions in order to investigate the effect of temperature and strain rate. A Nanoindenter XP® entirely set into a climatic chamber was used to perform the nanoindentation tests. For all tests, an increase of the elastic modulus was observed from a threshold contact pressure value. This effect is similar to the anvil effect observed on polymers: in confined geometry, the elastic modulus increases versus hydrostatic pressure. For the tribofilm, in the studied range, this effect is enhanced at high temperature and low strain rate. Furthermore, when the temperature increases, a change in the rheological behavior of the tribofilm is observed. Up to about 50°C, the tribofilm exhibits viscoplastic behavior — the hardness increases versus strain rate — and above 50°C, the hardness decreases versus strain rate (“shear thinning-like” behavior).

Atomic-Scale Coordination Effects on the Initial Stage of Passive Film Formation in Fe-Cr Alloys

2020 ◽  
Vol MA2020-02 (8) ◽  
pp. 1161-1161
Author(s):  
Yusi Xie ◽  
Minglu Liu ◽  
Ashlee Aeillo ◽  
Karl Sieradzki
Keyword(s):  
Passive Film ◽  
Film Formation ◽  
Atomic Scale ◽  
Initial Stage

Influence of Surface Strain on Passive Film Formation of Duplex Stainless Steel and Its Degradation in Corrosive Environment

2019 ◽  
Vol 166 (11) ◽  
pp. C3071-C3080 ◽  
Author(s):  
Cem Örnek ◽  
Marie Långberg ◽  
Jonas Evertsson ◽  
Gary Harlow ◽  
Weronica Linpé ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Duplex Stainless Steel ◽  
Passive Film ◽  
Film Formation ◽  
Surface Strain ◽  
Corrosive Environment

Kinetics of Passive Film Formation on Scratched Bare Surfaces of Stainless Steels in Magnesium Chloride Solutions

CORROSION ◽  
1993 ◽  
Vol 49 (11) ◽  
pp. 877-884 ◽  
Author(s):  
D. Li ◽  
X. Mao ◽  
R. Zhu
Keyword(s):  
Passive Film ◽  
Stainless Steels ◽  
Magnesium Chloride ◽  
Film Growth ◽  
Strong Electric Field ◽  
Film Formation ◽  
Adsorbed Layer ◽  
Passive Film Growth ◽  
Kinetics Of ◽  
Bare Surface

Abstract Kinetics of passive film formation on the bare surface of scratched stainless steels SS in magnesium chloride (MgCl2) solutions were studied using the rapid scratching technique under potentiostatic conditions. An experimental device was designed to record data at the rate of 20,000 points/s, with the rotating rate of the specimen at 3,000 rpm and a scratch scar length of about 4.6 mm to 4.8 mm. A new phenomenon was observed in that two peaks were seen rather than a continuous decay in the curve of current decay on scratched SS in MgCl2 solutions. Current decayed steeply to approximately passive current within about 2.5 ms to 3 ms after the diamond knife was moved away from the specimen. Current rose again for about 2 ms to 3 ms. This phenomenon was considered to represent the processes of adsorbed layer formation on the bare surface and transformation of the adsorbed layer into a passive film. Results were affected by the recording rate of experimental data, the specimen rotating rate, and the scratch scar length. The kinetics of passive film growth were shown empirically by i(t) = I0exp(−βt) with I0 and β being constants. Passive film growth was controlled by ion conduction in a strong electric field, as defined by i = A exp(BV/x).

scholarly journals Optical and electrochemical studies of passive film formation in amorphous Ni‐Cr‐P‐C alloys

1989 ◽  
Vol 66 (8) ◽  
pp. 3942-3945
Author(s):  
D. B. Hagan ◽  
B. W. Sloope ◽  
V. A. Niculescu
Keyword(s):  
Passive Film ◽  
Film Formation ◽  
Electrochemical Studies

Observations on the Anodic Behavior off Nickel and Chromium: Surface Topography and Temperature Effect

CORROSION ◽  
1966 ◽  
Vol 22 (2) ◽  
pp. 32-38 ◽  
Author(s):  
J. R. MYERS ◽  
W. B. CROW ◽  
F. H. BECK ◽  
R. K. SAXER
Keyword(s):  
Activation Energy ◽  
Surface Topography ◽  
Passive Film ◽  
Acid Concentration ◽  
Passive State ◽  
Effect Of Temperature ◽  
Nickel Surface ◽  
Passive Region ◽  
Potential Region ◽  
Metallographic Examination

Abstract Metallographic examination of anodically polarized nickel and chromium after long-time exposure at selected active, passive and transpassive potentials in H2-saturated, IN H2SO4 at 25 C (77 F) revealed significant differences in surface topography. Etch figures, present only in the trans-passive state, supported the belief that “active patches” are generated in passive films of these metals at potentials more noble than the passive region. The difference in nature of nickel surface in the early trans-passive region and visible oxygen evolution region is discussed. Effect of temperature on passive nickel (i.e., nickel in passive potential region) over the range 25 to 95 C (77 to 203 F) was determined for H2-saturated 0.5, 1, 5 and ION H2SO4 (pH = 0.85 to −1.05). Apparent activation energies for dissolution of passive nickel were determined. Inflection temperature (Ti) above which “active patches” apparently are formed in passive film was dependent on acid concentration according to the expression 1/Ti × 103 = −0.11 pH+ 3.04 over the pH range investigated and was independent of the direction from which the temperature was approached. The change in apparent activation energy (ΔQ) was a function of direction from which the temperature was approached. Measurements in which temperature was increased stepwise showed that ΔQ is related to pH by the expression ΔQ (kg - cal/mole) = 15,4 pH - 4.7 for acid concentrations studied. Because Ti and ΔQ are dependent on acid concentration, Seeger's activation energy for crystallization of a very thin pseudomorphic film and Kramer's exo-electron emission temperature which are independent of concentration cannot be used to explain fully generation of “active patches” in a passive film as proposed by previous investigators.

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