ISO16925 涂料和清漆.涂層耐壓力水噴射的測(cè)定
1 ScopeThis International Standard specifies a test method for the assessment of the resistance of coatings topressure water-jetting. The test method simulates the effects pressure water-jetting has on a coating.5 Apparatus and materialsOrdinary laboratory apparatus, together with the following:5.1 Pressure water-jet, consisting of a high-pressure pump and a nozzle.A high-pressure pump conveys the water from a storage bin. To avoid influences from variations inpressure, it is necessary that the pressure and the volumetric flow rate be adjustable at the nozzledescribed below.The water temperature shall be adjustable to ± 2 °C.The temperature shall be adjusted in accordance with Annex A. Necessary safety devices on the pressureside of the unit, as e.g. pressure relief valve and by-pass valve, shall exist. If the jetting is unsteady, a flowcalming section may be installed in front of the nozzle. A pulsation of the water jet at the opening of thepump is inadmissible. In order to reach a reproducible result, the nozzle shall be solidly mechanicallyfixed and the test specimen shall be secured against slipping. For the adjustment of the volumetric flowrate, a nozzle with a jet angle of 25° and a volumetric flow rate of 6 l/min at 2 MPa (20 bar) is required(see Annex A).The following technical data should be attainable:— volumetric flow rate: 8 l/min to 14 l/min— pressure: 4 MPa (40 bar) to 13 MPa (130 bar)— temperature: 20 °C to 80 °C— jetting time: 10 s to 300 sFigure 1 shows the schematic construction of a pressure water-jet apparatus which is specially built for these tests. Key1 flow calming section2 high-pressure valve, height adjustable3 test specimen4 clamping element 5 feed tank6 floating valve with filter7 water shortage safeguard8 heating9 base frame, moveable10 temperature sensor 11 high-pressure pump12 by-pass valve 13 pressure relief valve14 pressure transmitter8.1 Introducing the cut or the scribeMake sure that the test specimen is securely fastened when introducing the cut or the scribe.Introduce both of the cuts or scribes vertically through the coating into the substrate using the cuttingor scribing tool, as shown in Figure 2. The depth of the cut or scribe into the substrate should be asminimal as possible. The length of the first cut or scribe shall be at least 100 mm, if the geometry of thepart allows that. At an angle, introduce a second cut or scribe with a minimum length of 20 mm. Thecuts or scribes shall be introduced straight-line at an angle of approximately 30°. An automatic cuttingor scribing device may be used. Residues of the coating shall be removed from the cut or scribe.NOTE The depth of the cut or scribe into the substrate influences the result.The cutting or scribing tools should be checked regularly and replaced if necessary. Figure 2 — Introducing the cuts or scribes (St Andrew’s cross)
8.2 TestingAfter inserting the test specimen into the apparatus (e.g. using a spacer block), calibrate the spacebetween test specimen and nozzle.Operate the pressure water-jetting apparatus at room temperature.Three test methods (A, B, or C – see Table 1) are preferred as well as three possible scribing tools (C, L, orS – see 5.3). The test method to be applied, the scribing or cutting tool to be used, and the water pressureshall be agreed.Table 1 — Test methods | Test method | Water Temperature
℃ | Impact angle | Space between nozzle and sample （mm） | Flow rate
（L/min） | Duration of
jetting |
| A | 60±2 | 90±2 | 100±1 | 11.3±0.2 | 30±1 |
| B | 60±2 | 90±2 | 100±1 | 11.3±0.2 | 60±1 |
| C | 60±2 | 90±2 | 100±1 | 11.3±0.2 | 60±1 |
For jetting, deionized water should be used.When using automatic and manual devices, fasten the test specimen so that the water jet impacts asshown in Figure 3. The jet impacts in the middle above the point of intersection onto the longer one of both cuts/scribes.
Figure 3 — Jetting area9 Evaluation9.1 GeneralDamage is recognizable when the coating loosens or flakes, regardless of which coat sustains the damage.9.2 Evaluation with pictures to compareCarry out the evaluation visually, comparing the specimen with the pictures.In the course of the visual evaluation, a characteristic value is laid down by comparing with theillustrations in Figures 4 to 9. A characteristic value between 1 and 5 results, depending on the degreeof damage. No damage corresponds to the characteristic value 0. In addition to the evaluation, ifapplicable, the attribution of the separation from the main separation level or to the respective filmshall be indicated.The result of the visual assessment is indicated in dependence of the applied method, for example:— method A: characteristic value A;— method B: characteristic value B;— method C: characteristic value C.NOTE In addition, by measuring the areas of flaking (maximum width, in millimetres, or area, in squaremillimetres), the overall damage can be evaluated. The overall damage is calculated by summing up all damagedareas of the test specimen. Even the smallest areas of flaking are measured and calculated, and all areas added tothe overall damage.
Figure 5 — Characteristic value 1 for pressure water-jet damage
Figure 6 — Characteristic value 2 for pressure water-jet damage
Figure 7 — Characteristic value 3 for pressure water-jet damage
Figure 8 — Characteristic value 4 for pressure water-jet damage
Figure 9 — Characteristic value 5 for pressure water-jet damage Annex A(normative)Calibration of the test apparatusA.1 Apparatus and materialsOrdinary laboratory apparatus, as well as the following.A.1.1 Temperature measuring device, with sensor, capable of measuring to 0,5 °C.A.1.2 Balance, weighing to 10 g.A.1.3 Time measuring device (swatch), capable of measuring ± 0,1 s.A.1.4 Container, for the determination of the volumetric flow rate for at least 20 l of water.A.1.5 Plastic block, made of polystyrene rigid plastic foam.The kind of the polystyrene rigid plastic foam shall be agreed by the interested parties.A.1.6 Length measuring device, capable of measuring ± 0,1 mm.A.2.4 Calibration of the water jetThe conditions for the calibration of the jetting are in accordance with method B. For the calibration ofthe jetting, a stainless steel precision flat film extrusion die with a volumetric flow rate of the nozzle of6 l/min at 2 MPa (20 bar) and a jet angle 25° is used. This nozzle is required to produce an even liquiddistribution during the entire jetting.When using an automatic pressure-water apparatus, fasten the polystyrene rigid plastic foam in theapparatus so that the jet cannot move the block. When using a manual apparatus, fasten the block in asimilar fixture.After jetting, the length and the width of the impact are measured. See Figure A.1.The mean length of the impact shall be (73 ± 5) mm and the mean width (8 ± 1) mm on average.
Figure A.1 — Measures of the washed-out areas in the polystyrene rigid plastic foam 蒸汽噴射試驗(yàn)機(jī)滿足測(cè)試規(guī)范汽車廠家：寶馬、奔馳、通用、大眾、福特、沃爾沃等規(guī)范（AA-0136、DIN 55662、ISO16925，DBL 7381，GM9531P、PV1503、VOLVO STD 423-0015，VOLVO VCS 1029 54719、FLTM BO 160-04、MS210-07，PSA D23 5376，Renault D25 2018/-A-2001 ，GMW16745-2012方法B，TPJLR-52.561-2009）
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