SurTec® 650

SurTec ® 650
chromitAL TCP
Properties
• hexavalent chromium free passivation for aluminium
• based on trivalent chromium
• liquid concentrate
• excellent bare corrosion protection comparable to hexavalent passivations
• also works on alloyed and casted aluminium
• suitable as pretreatment before laquering, powder coating and gluing
• easy to handle in immersion, spray and wipe application
• produces an iridescent, faintly blue to tan and visible layer
• SurTec 650 meets or exceeds MIL-DTL-81706 and MIL 5541 for bare corrosion
(336 h in NSS per ASTM B-117, respectively, DIN 50021 SS)
• low contact resistance, < 0.8 mOhm/cm 2
• heat resistant up to 100 °C with minimal loss in corrosion resistance
• applied forUS-patent: 6,375,726; 6,511,532; 6,521,029; 6,527,841
Application
SurTec 650 is diluted with DI-water.
concentration: spray immersion
SurTec 650 250 ml/l (100-500 ml/l) 200 ml/l (100-500 ml/l)
make-up: Before make up clean the tank thoroughly. For new tanks or
new liners, leach with 10 % sulfuric acid, then rinse before use.
Add DI-water to SurTec 650, stirring vigorously. Afterwards,
measure the pH-value and adjust it to 3.9 if necessary.
temperature: 40 °C (30-40 °C)
pH-value: 3.9 (3.70-3.95)
slowly, with constant mixing, adjust with 5 % sulfuric acid or
1 % sodium hydroxid solution
application time: at 40 °C 1 min (0.5-1 min) as pretreatment before coating
2 min (1-3 min) as bare protection
at 30 °C 2 min (1-4 min) as pretreatment before coating
4 min (2-6 min) as bare protection
spraying pressure: 1 bar (0.5-1.5 bar)
agitation: not necessary
tank material: stainless steel or steel with acid and fluoride resistant coating
filtration: necessary (min. 2 circles/h)
heating: necessary; of acid and fluoride resistant material
cooling: not necessary
exhaustor: required for worker's protection

hints: During storage a slight precipitation may occur which does not
impair the quality and the function of the product.
Prior to the passivation with SurTec 650 the aluminium surface
must be cleaned and deoxidized thoroughly. The surface must
be water-break free.
Standard procedures for immersion are:
For aluminum alloys with < 1 % Silicon:
1. mild alkaline degreasing, SurTec 133
2. alkaline etching, SurTec 181
3. deoxidizing, SurTec 495
For aluminum alloys with > 1 % silicon:
1. mild alkaline degreasing, SurTec 136
2. deoxidizing, SurTec 495
Standard procedure for spray is:
1. acid degreasing, SurTec 472 / SurTec 086
Treated surfaces with SurTec 650 can be coated immediately
after drying or stored as long as they are protected from contamination
and temperature extremes. For optimum results, parts
should stand for 24 h before subsequent coatings are applied.
maintenance: Analyse and adjust pH-value by using a frequently calibrated
pH-meter. Analyse and adjust the concentration regularly.
consumption: The consumption strongly depends on the drag-out (for the
exact determination of the drag-out see SurTec Technical
Letter 11). As a general orientation can be taken:
Analysis
Sample Preparation
15-25 ml SurTec 650 concentrate are sufficient for treating 1 m 2
surface (drag-out included).
Take the sample at a homogeneously mixed position and let it cool down to room
temperature. If dull, allow to settle and decant or filter.
Concentration via chromium content
page 2
reagents: 10 % sodium hydroxide, 30 % H 2O 2, 17 % hydrochloric acid,
potassium iodide, 0.1 N sodium thiosulfate, 1 % starch solution
process: Pipette 100 ml passivation bath into a 250 ml Erlenmeyer flask,
and add 20 ml sodium hydroxide solution. Then add appr. 5 ml
H 2O 2, stirr for 5 min, add another 5 ml H 2O 2, stirr for 5 min at
room temperature and boil the solution for 30-40 min. It is very
important to evaporate excessive H 2O 2. The volume must not
evaporate below 50 ml.
Chill the solution, add demineralised water up to about 100 ml
and filter it using a fine grained filter paper (blue band). Rinse
the filter with 5 ml DI-water. The filtrate must be clear and free
of precipitates.

Add 40 ml hydrochloric acid to the filtrate (colour change from
yellow to orange). Add about 1 g potassium iodide, titrate with
0.1 N sodium thiosulfate until the solution is only slightly
yellowish, then add some starch solution and continue to titrate
until the blue colour disappears.
calculation: consumption in ml · 1.613 = Vol% SurTec 650
Technical Specification
at 20 °C appearance density pH-value
(g/ml) concentrate
SurTec 650 green liquid 1.005 (1.000-1.010) 3.8 (3.6-4.0)
Ingredients
• trivalent chromium salts
Stock Keeping
To prevent interruptions due to logistic problems, a certain stock is indispensable.
We recommend to keep the following amounts per 1000 l bath:
Passivation SurTec 650 500 kg
Ecology
Used solutions of SurTec 650 and its rinsing waters have to be worked up and disposed
corresponding to national and local regulations. SurTec 650 itself is slightly
hazardous for water, Water Hazard Class 1 (self-assessment).
Product Safety
SurTec 650 is not subject to classification according to General EC Classification
Guidelines for Preparations.
Please consult also the EC safety data sheet.
Guarantee
page 3
Our guarantee extends to the continuous quality of our products as they leave our
factory and not to their usage in the field. Our technical service will be pleased to
answer any question you may have concerning operation and use of our products:
Fax: 0(049)-6251/171-844, Tel.: 0(049)-6251/171-744, e-Mail: TZ@SurTec.com.
20.06.2005/SV, PV