SH/T 0620-1995 Determination of corrosion of cast aluminium alloys by engine coolants under heat-transfer conditions

Summary page. This page is a compiled excerpt/summary of the standard — it is not the full standard text and does not replace it. Verify every value against the official standard and the product certificate before use.

SH/T 0620-1995 specifies a method for determining the corrosion of commonly used cast aluminium alloys by engine coolants under the heat-transfer conditions that exist in an engine aluminium cylinder head.

Evidence note: the content of this page was compiled from the original text of this standard held in the Origin Standard library (entries marked “〔to be verified〕” indicate 〔source text unclear〕); for individual values and the current status of the standard, please refer to the original standard pages and the product certificate. Verification note: the marks 〔to be verified〕 and 〔source text unclear〕 identify specific points that still require checking against the original standard and do not mean that verification has been completed. Do not use these values or steps directly as a basis for work.

Scope: This standard specifies a method for determining the corrosion of commonly used cast aluminium alloys by engine coolants under the heat-transfer conditions that exist in an engine aluminium cylinder head. This standard is applicable to engine coolants and their concentrates. Not applicable: not provided in the available material.

Principle: A cast aluminium alloy commonly used for engine aluminium cylinder heads is machined into a test specimen; after weighing, the test surface of the specimen is immersed in the engine coolant sample, pressure is applied to the sample with air, and the specimen is held at a constant temperature of 135 °C ± 1 °C for 168 h. After the test, the specimen is cleaned and weighed again, and corrosion is evaluated from the corrected change in specimen mass.

Apparatus: Heat-transfer corrosion test apparatus: FLY 93-135/168 engine coolant aluminium hot-surface corrosion apparatus (see Figure 7, as given in the source text; suspected to be Figure 1, to be verified (source text unclear)), or another type of corrosion test apparatus of equivalent performance. The FLY 93-135/168 corrosion apparatus consists of a heat-transfer corrosion chamber, a heater and a temperature controller; the components of the heat-transfer corrosion chamber include a glass vessel, O-ring seals, a top end plate and a bottom end plate. 5.1.1.1 Glass vessel: inner diameter 40 mm to 42 mm, wall thickness 3 mm to 4 mm, length 530 mm, with an O-ring groove at each end of inner diameter 48 mm, outer diameter 57 mm and depth 2.5 mm, made of heat-resistant glass able to withstand the test pressure (see Figure 2). 5.1.1.2 O-ring seals: fit the O-ring grooves at both ends of the glass vessel, dimensions in accordance with the relevant dimensions of GB 3452.1, made of silicone rubber. 5.1.1.3 Top end plate and bottom end plate: made of stainless steel (see Figure 2). 5.1.1.4 Heater: 200 W, 220 V electric heating mantle. 5.1.1.5 Temperature controller: capable of meeting the requirements of the test conditions of 135 °C ± 1 °C for 168 h continuous operation. A thermocouple or other thermal sensor is connected to the specimen. 5.1.1.6 Safety device: spring washer, safety valve or other safety pressure-relief device. 5.1.1.7 Thermometer: 0 °C to 200 °C, scale division 1 °C. 5.1.1.8 Safety shield: made of acrylic tube, inner diameter 115 mm to 120 mm, thickness 4 mm to 5 mm, with holes at both ends of the shield to allow air circulation inside it. 5.1.2 Ultrasonic cleaner: power about 50 W. 5.1.3 Vacuum drying oven: temperature control range 0 °C to 150 °C. 5.1.4 Vacuum pump: used with the vacuum drying oven. 5.1.5 Analytical balance: sensitivity 0.1 mg. 5.1.6 Microscope: magnification 10 to 30 times. 5.1.7 Desiccator.

Reagents and reference materials: 6.1 Anhydrous ethanol: chemically pure. 6.2 Sodium chloride: analytical grade. 6.3 Chromium trioxide: chemically pure. 6.4 Phosphoric acid: chemically pure (85 %). Caution: phosphoric acid is a strong acid and chromium trioxide is a highly toxic oxidizing agent; avoid contact with skin and eyes. 5.2.1 Cast aluminium alloy specimen (referred to as the specimen): chemical composition silicon 5.5 % to 6.5 %, copper 3.0 % to 4.0 %, iron < 1.2 %, manganese < 0.8 %, magnesium 0.1 % to 0.5 %, nickel < 0.5 %, zinc < 1.0 %, titanium < 0.25 %, aluminium balance. Diameter 65 mm, thickness 13 mm, with one thermocouple hole and one thermometer hole (see Figure 2). 5.2.2 Abrasive cloth (or abrasive paper): grit 150, 180 and 240. 5.2.3 Metallographic abrasive paper: abrasive grain size W20 (20 μm to 14 μm). 5.2.4 Plastic scraper: made of a material softer than the cast aluminium alloy specimen, such as polyethylene or polypropylene, with one edge sharpened. 5.2.5 Tweezers. 5.2.6 Air source: air supplied by an air compressor or a piped air source, capable of providing dry, clean air. 5.2.7 Cleaning agent: neutral cleaning agent. 5.2.8 Distilled water: meeting the grade 3 water requirements of GB/T 6682. 5.2.9 Soft brush: soft, long-handled palm-fibre brush. 5.2.10 Pumice powder. Corrosive water (7.3.1): dissolve 220 mg of sodium chloride in 1 L of distilled water. Note: if a large amount of corrosive water is needed for the test, 10 times the amount of sodium chloride may be dissolved in 1 L of distilled water to prepare a concentrated corrosive water. When required, dilute 1 volume of the concentrate with 9 volumes of distilled water. Mixed chromium trioxide and phosphoric acid cleaning solution (Note to 8.6.2): dissolve 20 g of chromium trioxide in 980 g of 1:1 (by volume) phosphoric acid solution.

Key conditions: Specimen temperature: 135 °C ± 1 °C Constant-temperature duration: 168 h (one week) Initial pressurization of the heat-transfer corrosion chamber: 140 kPa (compressed air) Pressure in the heat-transfer corrosion chamber when the specimen temperature reaches 135 °C: 190 kPa to 200 kPa Adoption note: in the original standard the initial pressure of the heat-transfer corrosion chamber was 138 kPa, and at a specimen temperature of 135 °C the pressure was maintained at 193 kPa.

Calculation and results: The heat-transfer corrosion rate R (mg/cm²) of the sample is calculated as follows: R = [(m₁ - m₂ + B) / A] × 1000 where: m₁ — mass of the specimen before the test, g; m₂ — mass of the specimen after the test, g; B — blank cleaning mass loss of the specimen, g; A — heat-transfer surface area of the specimen inside the O-ring seal, cm². Note: the formula in the source text is 〔source text unclear〕 and contains noise ("rm:一(m,+B)1 x 1000"); it has been arranged from the context and the symbol definitions; to be verified (source text unclear).

Quality control: Precision and bias: precision and bias are not yet specified in this standard. 10.2 When the heat-transfer corrosion rate results of a sample are in dispute, a second test shall be carried out, and the result shall be reported as the arithmetic mean of the two test results, rounded to 0.1 mg/cm².

Normative references: GB 3452.1 Hydraulic and pneumatic O-ring rubber seals — dimension series and tolerances GB/T 6682 Water for analytical laboratory use — specification and test methods SH/T 0065 Sampling of engine coolant or rust inhibitor test samples and preparation of their aqueous solutions SH/T 0069 Determination of pH of engine antifreezes, rust inhibitors and coolants ASTM D4341-89 (equivalent adoption)

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