Filiform Corrosion Test Procedure for Painted Aluminum Wheels and Painted Aluminum Wheel Trim

2015 ◽  
Author(s):  
Keyword(s):  
Corrosion Test ◽  
Test Procedure ◽  
Filiform Corrosion

scholarly journals Development of Proving Ground Field Test for Establishment of Vehicle Accelerated Corrosion Test Procedure in Malaysia

2019 ◽  
Vol 16 (1) ◽  
pp. 6348-6356
Author(s):  
L. Anuar ◽  
A. Amrin ◽  
R. Mohammad ◽  
S. A. Aziz ◽  
M. Toozandehjani
Keyword(s):  
Field Test ◽  
Corrosion Test ◽  
Corrosion Behaviour ◽  
Test Procedure ◽  
Field Tests ◽  
Ground Field ◽  
Accelerated Corrosion ◽  
Accelerated Corrosion Test ◽  
Service Conditions ◽  
External Test

This paper presents the field tests conducted as part of activity to establish the vehicle accelerated corrosion test procedure in Malaysia, initiated by the national car manufacturer company, PROTON, Malaysia. Vehicle accelerated corrosion test is a combination of corrosion exposures and durability cycles to accelerate the corrosion process and detect potential failures that may occur during in-service conditions. PROTON conducts the vehicle accelerated corrosion test at external test centres in overseas. However, due to the different climatic of test location, some of the corrosion problems were found to be varied and many did not address the actual corrosion problems detected in Malaysia markets. Hence, the primary aim of this study is to establish a suitable corrosion driving procedure to accommodate the hot and humid environment using facilities in PROTON Test Track. Three corrosion driving procedures were designed based on the number of corrosion exposures and designated as Field Tests 1, 2 and 3. Analysis ruled out that Field Test 3 provides moderate corrosion rate of 0.077-0.842 mm/year and potentially to be the best suited for accelerated corrosion test procedure in Malaysia due to its close replication of actual cosmetic corrosion behaviour observed in Malaysia.

Study of factors affecting corrosion of aluminum automotive wheels

1993 ◽  
Vol 51 ◽  
pp. 1182-1183
Author(s):  
H. K. Plummer ◽  
R. N. Simmons ◽  
R. W. Ocobock ◽  
T. A. Honey ◽  
M. C. Paputa Peck
Keyword(s):  
Corrosion Test ◽  
Uv Exposure ◽  
Uv Absorbance ◽  
Water Spray ◽  
Surface Layers ◽  
Accelerated Corrosion ◽  
Factors Affecting ◽  
Accelerated Corrosion Testing ◽  
Filiform Corrosion ◽  
Accelerated Corrosion Test

Aluminum automotive wheels, which have been used since the mid 1970’s, have proven to be very rugged, but early wheels discolored with time. Since 1976 the machined “bright” exterior surfaces, have been coated with a chromium based “conversion” pretreatment, and painted with a “clearcoat” of polyester or acrylic to preserve appearance. These coated wheels can exhibit “filiform” corrosion between the Al surface and the clearcoat (Fig. 1). The corrosion is filamentous and closely follows aluminum grain boundaries. Corrosion results from oxidation of the aluminum (anode) in the presence of water and oxygen at a break (cathode) which intrudes through the clearcoat and conversion coat into the aluminum (Fig. 2). Current specifications require ≤ 1.6 mm filiform corrosion from a scratch after 400 h of accelerated corrosion testing. This paper correlates accelerated corrosion with the composition of the clearcoat paint, the UV absorbance of the paint and the microstructure of the Al / Cr conversion coat / clearcoat interface to learn the necessary parameters to produce Al wheels with enhanced protection. Production Al wheels, from a variety of sources, wheels prepared to our specifications and a design of experiments (DOE) wheel series prepared in our laboratories were examined.The accelerated corrosion test exposes the test piece to UV weathering (400 h) with four water spray cycles every 23 h. After UV exposure the surface is scratched through the surface layers into the Al metal with a carbide scribe, followed by exposure to HCl vapor (1 h).

Benefits from Computerized Adaptive Testing as Seen in Simulation Studies

1999 ◽  
Vol 15 (2) ◽  
pp. 91-98 ◽  
Author(s):  
Lutz F. Hornke
Keyword(s):  
Measurement Error ◽  
Computerized Adaptive Testing ◽  
Test Procedure ◽  
Adaptive Testing ◽  
Parameter Estimates ◽  
Simulation Studies ◽  
Computerized Adaptive Test ◽  
Item Banks ◽  
Item Parameters ◽  
General Reliability

Summary: Item parameters for several hundreds of items were estimated based on empirical data from several thousands of subjects. The logistic one-parameter (1PL) and two-parameter (2PL) model estimates were evaluated. However, model fit showed that only a subset of items complied sufficiently, so that the remaining ones were assembled in well-fitting item banks. In several simulation studies 5000 simulated responses were generated in accordance with a computerized adaptive test procedure along with person parameters. A general reliability of .80 or a standard error of measurement of .44 was used as a stopping rule to end CAT testing. We also recorded how often each item was used by all simulees. Person-parameter estimates based on CAT correlated higher than .90 with true values simulated. For all 1PL fitting item banks most simulees used more than 20 items but less than 30 items to reach the pre-set level of measurement error. However, testing based on item banks that complied to the 2PL revealed that, on average, only 10 items were sufficient to end testing at the same measurement error level. Both clearly demonstrate the precision and economy of computerized adaptive testing. Empirical evaluations from everyday uses will show whether these trends will hold up in practice. If so, CAT will become possible and reasonable with some 150 well-calibrated 2PL items.

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