DELPHI-I - DELPHI DX551800
CORROSION PROTECTIVE COATINGS - CHROMIUM FREE ZINC RICH INORGANIC WITH TOPCOAT
|Publication Date:||1 February 2008|
This specification covers the basic requirements for non-oily corrosion protective coatings consisting of suitable pretreatment, zinc rich inorganic resin coating and aluminum rich organic topcoat. All treatments, coatings, and topcoats must be chromium free.
The specification number shown in the title is a generic number for the chromium free zinc-aluminum coating. Table 1 shows the specification number to be used on the drawings and reflects the basic requirements of the specification.
Drawing call out example: DX551801 per DX551800.
This example from Table 1 indicates a coating with a torque @ 28.3 kN tension of 48 ± 8 and a coefficient of friction of 0.13 ± 0.03. The coating must withstand a minimum of 480 hours neutral salt spray without evidence of base metal corrosion (red rust). The color will be silver unless otherwise specified. The presence of a suffix after the specification number (example: DX551801-F) indicates an approved source supplemental qualification requirement, as described in Section 11.
Specific requirements shown on the part drawing shall take precedence over any requirements in this specification or may be in addition to the requirements of this specification.
The maximum cure temperature of these coatings is as specified in Table 2.
This coating is suitable for externally and internally threaded ferrous parts M6 and greater and nonthreaded ferrous parts where high levels of corrosion protection and freedom from hydrogen embrittlement are required. When applied over steel that is to be coupled to aluminum, this coating provides exceptional galvanic protection. For parts with recessed drives this coating is not recommended.
Use of this finish on threaded surface and/or bearing surface of joints could affect the torque-tension relationship. It is recommended that a torque-tension study of the fastener joint be performed before releasing this finish on a new application.
NOTE 1: The use of this finish in dissimilar galvanic couples other than steel to aluminum should be evaluated for satisfactory performance
NOTE 2: Use of vibratory feeders can cause coating damage and produce powdery deposits in the feeder.