Electroless plating properties
Chemical Resistance
Chemical resistance is one of the key properties of electroless nickel plating coatings, as it determines whether the coated component is suitable for operation in environments containing aggressive or potentially reactive chemical substances.
NIPLATE® coatings (see NIPLATE® coatings), thanks to their nickel–phosphorus alloy composition, generally provide good chemical stability across a wide range of environments. In particular, high-phosphorus coatings, such as NIPLATE® 500, show higher chemical resistance than medium-phosphorus coatings, such as NIPLATE® 600. For this reason, NIPLATE® 500 is generally preferred in applications where chemical resistance is the primary functional requirement.
It is important to note that the coating’s chemical resistance depends not only on the Ni–P alloy composition, but also on the operating conditions (temperature, aeration, substance concentration).
Evaluation criteria for chemical resistance
The chemical resistance of electroless nickel coatings is commonly evaluated in terms of the corrosion rate of the coating itself, expressed as thickness loss over time. The data reported in the literature and in reference tables provide useful guidance for an initial coating selection, but they do not replace experimental verification on the actual component.
The following tables report chemical resistance data for electroless nickel in contact with industrial chemicals and food and food media, taken from the technical reference literature [Gawrilov, G.G.: Chemische (stromlose) Vernicklung, Eugen G. Leuze Verlag, Bad Saulgau, 1974], [Riedel, W.: Funktionelle Chemische Vernicklung, Eugen G. Leuze Verlag, Bad Saulgau, 1989].
These tables should be regarded as indicative of the chemical compatibility of the coating only and do not indicate corrosion protection of the base material.
The overall performance of the coated component depends largely on the type, metallurgical quality, and surface condition of the base material.
The listed data can be used for a preliminary assessment, but the chemical compatibility of NIPLATE® coatings must always be verified by field testing or specific tests, since even minor variations in contact conditions (temperature, concentration, aeration, exposure time) can significantly affect coating behavior.
Table of the chemical resistance of electroless nickel coatings to various chemicals
Legend
- A: layer corrosion rate < 2.5 µm/year – excellent chemical compatibility, no or negligible coating corrosion.
- B: layer corrosion rate < 12.5 µm/year – good chemical compatibility, limited coating corrosion.
- C: layer corrosion rate < 25 µm/year – poor chemical compatibility, appreciable coating corrosion.
- D: layer corrosion rate > 25 µm/year – very poor chemical compatibility, severe coating corrosion.
| Medium | Conc. % by weight | Temp. (°C) | Aeration | Medium phosphorous Electroless Nickel Plating resistance | High phosphorous Electroless Nickel Plating resistance |
|---|---|---|---|---|---|
| Acetic acid | 5 | 20 | no | C | C–B |
| Acetic acid | 5 | 20 | yes | D | - |
| Benzoic acid | saturation | 20 | no | -- | D |
| Boric acid | saturation | 20 | no | C | C |
| Citric acid | 5 | 20 | no | A | A |
| Hydrochloric acid | pH 1.5 | 20 | no | D | D |
| Hydrochloric acid | pH 1.5 | 20 | yes | D | D |
| Chromic acid | 2–100 | 20 | no | -- | D |
| Formic acid | 88 | 20 | no | -- | B |
| Fluoroboric acid | 25 | 20 | no | -- | D |
| Malic acid | saturation | 20 | no | -- | A |
| Nitric acid | 2–100 | 20 | no | -- | D |
| Oleic acid | 100 | 20 | no | A | A |
| Oxalic acid | saturation | 20 | no | -- | A |
| Picric acid | 100 | 20 | no | -- | D |
| Hydrogen sulfide | 100 | 20 | no | -- | A |
| Sulfuric acid | 1–5 | 20 | no | D | C–D |
| Sulfurous acid | 2–60 | 20 | no | -- | D |
| Stearic acid | saturation | 20 | no | A | A |
| Fatty acids | 100 | 20 | no | -- | B |
| Demineralized water | -- | 20 | no | A | -- |
| Demineralized water | -- | 20 | yes | A | -- |
| Demineralized water | -- | 49 | no | A | -- |
| Demineralized water | -- | 80–82 | no | A | A |
| Distilled water | -- | 20 | no | A | A |
| Sea water | -- | 20 | no | -- | A |
| Aluminum chloride | saturation | 20 | no | -- | D |
| Aluminum sulfate | saturation | 20 | no | B | B |
| Ammonium chloride | saturation | 20 | no | -- | B |
| Ammonium hydroxide | 5–28 | 20 | no | -- | C |
| Ammonium nitrate | saturation | 20 | no | B | B |
| Ammonium phosphate | saturation | 20 | no | C | -- |
| Gasoline | 100 | 20 | no | A | A |
| Aviation gasoline | 100 | 20 | no | -- | A |
| Benzene | 100 | 20 | no | A | A |
| Butadiene | 100 | 25 | no | -- | A |
| Butanol | 100 | 20 | no | -- | A |
| Calcium chloride | 48.5 | 20 | no | A | A |
| Calcium hydroxide | saturation | 60 | no | -- | A |
| Calcium nitrate | saturation | 20 | no | -- | A |
| Carbon tetrachloride | 100 | 20 | no | A | A |
| Kerosene | 100 | 20 | no | -- | A |
| Chlorine | 100 | 20 | no | -- | B |
| Chlorine (dry gas) | 100 | 20 | no | A | |
| Rosin | 100 | boiling | no | -- | A |
| Diisobutyl phthalate | 100 | 20 | no | A | -- |
| Dichloroethane | 100 | 20 | no | -- | A |
| Dichloromethane | 100 | 20 | no | -- | C |
| Dimethylbenzene | 100 | 20 | no | -- | A |
| Ethanol | 100 | 20 | no | A | A |
| Ethylene | 100 | 20 | no | -- | A |
| Ethylene dichloride | 100 | 83 | no | -- | A |
| Ethylene glycol | 100 | 20 | no | -- | A |
| Phenol | saturation | 90 | no | -- | A |
| Iron(II) chloride | 100 | 20 | no | -- | D |
| Iron(II) nitrate | 100 | 20 | no | -- | D |
| Iron(II) sulfate | 100 | 20 | no | -- | D |
| Formaldehyde | 37 | 20 | no | -- | B |
| Glucose | saturation | 20 | no | A | A |
| Glycerine | 100 | 20 | no | -- | A |
| Lithium chloride | saturation | 20 | no | -- | A |
| Magnesium chloride | 2–50 | 20 | no | -- | A |
| Magnesium hydroxide | 2–100 | 20 | no | -- | A |
| Mercury chloride | saturation | 20 | no | -- | D |
| Methanol | 100 | 20 | no | A | A |
| Methyl ethyl ketone | 100 | 20 | no | -- | A |
| Nickel chloride | saturation | 20 | no | -- | C |
| Nickel sulfate | saturation | 20 | no | -- | A |
| Oleum | 20 | 20 | no | -- | D |
| Mineral oil | 100 | 20 | no | -- | A |
| Paraffin | 100 | 20 | no | -- | A |
| Tetrachloroethylene | 100 | 20 | no | -- | A |
| Petroleum | 100 | 20 | no | A | A |
| Lead acetate | saturation | 20 | no | -- | B |
| Lead nitrate | saturation | 20 | no | -- | A |
| Potassium carbonate | saturation | 20 | no | -- | A |
| Potassium chloride | saturation | 20 | no | -- | A |
| Potassium ferricyanide | saturation | 20 | no | -- | B |
| Potassium hydroxide | 2–50 | 20 | no | -- | A |
| Propane | 100 | 20 | no | -- | A |
| Copper(I) chloride | saturation | 20 | no | -- | D |
| Copper(II) nitrate | saturation | 20 | no | -- | D |
| Copper(II) sulfate | 2–30 | 20 | no | -- | C |
| Sodium bicarbonate | saturation | 20 | no | -- | B |
| Sodium borate | saturation | 20 | no | B | B |
| Sodium carbonate | saturation | 20 | no | A | B |
| Sodium chloride | saturation | 20 | no | -- | A |
| Sodium cyanide | 5 | 20 | no | C | B |
| Sodium phosphate | saturation | 20 | no | -- | A |
| Sodium hydroxide | 2–73 | 20–115 | no | A | A |
| Sodium hypophosphite | saturation | 20 | no | A | -- |
| Sodium sulfate | saturation | 20 | no | -- | A |
| Sodium sulfide | saturation | 20 | no | -- | A |
| Toluene | 100 | 95 | no | -- | A |
| Turpentine | 100 | 20 | no | -- | A |
| Trichloroethylene | 100 | 95 | no | -- | A |
| Trichloromethane | 100 | 61 | no | -- | B |
| Urea | 25 | 20 | no | A | A |
| Steam | -- | 425 | no | -- | A |
| Steam condensate | -- | 80 | no | -- | A |
| Vinyl chloride | 100 | 35 | no | -- | A |
| Zinc chloride | saturation | 20 | no | -- | B |
Table of the chemical resistance of electroless nickel coatings in contact with food
| Medium | pH | Vol. test [ml] | Duration Test [h] | Corrosion rate [µm/year] | Dissolved nickel [mg] | Daily nickel release [µg/l/day] |
|---|---|---|---|---|---|---|
| Vinegar | 2.9 | 470 | 1729 | 7.0 | 32 | 210 |
| Canned pineapple | - | 500 | 1681 | 0.3 | 0.8 | 6 |
| Chicken broth (3 tests at 95°C/203°F) | 6.0 | 200 | 312/502 | 1.0 | 2.0 | 19 |
| Coffee | 5.3 | 700 | 1729 | 9.9 | 25 | 240 |
| Coffee (4 tests at 95°C) | 4.8 | 200 | 312/554 | 4.7 | 18 | 200 |
| Cooked onions | - | 450 | 1702 | 0.8 | 1.6 | 10 |
| Mushrooms | - | 150 | 1681 | 0.6 | 3.3 | 7 |
| Gin (2 tests) | 7.5 | 150 | 3910 | 0.02 | 3.4 | 3 |
| Milk (2 tests at 2°C) | 6.4 | 950 | 1248/1633 | 0.04 | - | - |
| Buttermilk (2 tests at 2°C) | - | 950 | 1248/1633 | 0.6 | - | - |
| Lemonade | - | 950 | 1702 | 11.4 | 15 | 200 |
| Mayonnaise | 3.7 | 470 | 1681 | 0.2 | 0.9 | 6 |
| Canned corn | 6.2 | 250 | 1702 | 0.7 | 2 | 7 |
| Margarine (2°C) | - | 200 | 1633 | - | - | - |
| Vegetable oil | - | 470 | 1729 | - | - | - |
| Spanish olives | 3.7 | 250 | 1702 | 0.3 | 1.2 | 4 |
| Tomato puree | 4.2 | 400 | 1681 | 0.5 | 2.2 | 13 |
| Canned peas | 6.1 | 450 | 1702 | 0.2 | 0.3 | 2 |
| Rum | 5.8 | 150 | 3910 | 0.2 | 10 | 9 |
| Sardines in soybean oil | - | 30 (oil) | 1681 | - | - | - |
| Sherry | 3.8 | 150 | 3910 | 6.4 | 170 | 160 |
| Lemon juice | 2.3 | 800 | 1702 | 1.0 | 1.7 | 19 |
| Apple juice | 3.1 | 850 | 1702 | 1.2 | 1.5 | 18 |
| Tomato juice (2 tests) | 4.2 | 710 | 1321/1336 | 0.5 | 0.7 | 9 |
| Grapefruit juice | 3.2 | 900 | 1702 | 0.5 | 0.6 | 8 |
| Prune juice | - | 1000 | 1702 | 1.0 | 0.1 | 1 |
| Grape juice | 4.0 | 800 | 1702 | 1.8 | 2.6 | 29 |
| Tea | 2.6 | 750 | 1729 | 4.2 | 10 | 100 |
| Tea (4 tests at 95°C) | 2.6 | 200 | 312/554 | 9.0 | 7.5 | 84 |
| Tequila (2 tests) | 4.8 | 150 | 3910 | 0.4 | 15 | 14 |
| Eggs (2 tests at 2°C) | 8.3 | 300 | 1248/1633 | 0.2 | - | - |
| Scotch whisky | 5.3 | 150 | 3910 | 1.8 | 50 | 46 |
| Bean soup | - | 500 | 1702 | 0.7 | 0.2 | 1 |
| Mushroom soup | - | 250 | 1702 | 0.3 | 0.8 | 3 |
| Tomato soup | - | 250 | 1702 | 0.5 | 1.8 | 6 |
| Vegetable soup | - | 250 | 1702 | 1.2 | 2.5 | 9 |