Technical Comparison
Dacromet microstructure image
Electrostatic Spraying Metallographic Image
Metallographic image of zinc penetration
Metallographic image of zinc-nickel diffusion layer
A Comprehensive Comparison of Various Surface Treatment Technologies
| Comparison item |
Electroplated zinc |
Hot-dip galvanizing |
Dacromet |
Powder Zinc infiltration |
Zinc-aluminum multi-element co-diffusion |
Zinc-nickel diffusion layer |
| Pickling |
There is |
There is |
None |
There is |
None |
None |
| Hydrogen embrittlement |
There is |
There is |
None |
None |
None |
None |
| Neutral Salt Spray Test (h) |
≤100 |
≤480 |
≥1000 |
≥240 |
≥500 |
Up to 6,000 |
| Anti-sulfur dioxide |
Poor |
Poor |
Poor |
Poor |
Poor |
Good |
| Adhesion |
Better |
Better |
Poor |
Better |
Better |
Good |
| Hardness (HV) |
180-200 |
70-80 |
2H |
>250 |
>250 |
200-500 |
| Wear resistance |
Poorer |
Better |
Poor |
Better |
Good |
Good |
| Appearance uniformity |
Good |
Poor |
Good |
Better |
Good |
Good |
| Coordinating impact |
Smaller |
Big |
Smaller |
Smaller |
Smaller |
Smaller |
Note: Varies depending on the material and heat treatment process.
Residual stress on the surface of the spring clip
|
|
Residual stress in the 0° direction (MPa) |
Residual stress at 90° direction (MPa) |
| Before the zinc-nickel diffusion layer |
-49.5 ± 4.6 |
-69.0 ± 4.3 |
| -114.5 ± 30.9 |
-81.1 ± 27.4 |
|
| -70.0 ± 23.0 |
-63.0 ± 18.0 |
|
| After zinc-nickel plating |
-282.6 ± 4.6 |
-329.8 ± 8.5 |
| -195.8 ± 7.4 |
-299.8 ± 6.4 |
|
| -340.0 ± 15.5 |
-294.3 ± 19.8 |
Comparison of Fatigue Life Between Zinc-Nickel Plating and Dacromet (Wind Turbine Bolts)
Hardness of zinc-nickel diffusion layers after different materials and heat treatment conditions
| Hot-rolled low-carbon steel (Q235)—the hardness of the diffusion layer is slightly higher than that of the base material. |
| Product |
Sample No. |
Diffusion layer |
Average |
Matrix |
Average |
| HV0.025 |
HRB |
||||
| Gauge block |
1 |
200 208 189 |
199 |
65.5 65.0 66.0 |
66.0 (130 HV) |
| 2 |
198 232 215 |
215 |
67.0 65.5 65.0 |
66.0 (130 HV) |
|
| 3 |
232 203 232 |
222 |
70.5 69.5 66.5 |
69.0 (135HV) |
|
| 4 |
196 189 173 |
186 |
67.0 67.5 70.0 |
68.0 (135HV) |
|
| Spiral spike |
1-1 |
271 283 247 |
267 |
82.0 81.5 82.0 |
82.0 (170 HV) |
| 1-2 |
251 232 241 |
241 |
80.0 80.0 79.0 |
79.5 (165HV) |
|
| 2-1 |
226 215 221 |
221 |
82.5 81.5 82.0 |
82.0 (170 HV) |
|
| 2-2 |
208 215 205 |
209 |
80.0 81.0 79.0 |
80.0 (165HV) |
|
Hot-rolled medium-carbon steel (45 steel) and unquenched and tempered cast iron— the hardness of the diffusion layer is slightly higher than that of the base material.
| Product |
Diffusion layer |
Average |
Matrix |
Average |
| HV0.1 |
||||
| 45 steel |
351 374 353 351 356 |
357 |
276 274 271 270 276 |
273 |
| QT400-15 |
325 325 321 320 327 |
324 |
232 238 230 235 238 |
235 |
Carbon alloy steel subjected to quenching and tempering—hardness of the diffusion layer is slightly lower than that of the base material.
| Product |
Diffusion layer |
Average |
Matrix |
Average |
| HV0.1 |
||||
| Type II spring clip (60Si2CrA) |
433 429 436 414 429 |
428 (44.0 HRC) |
468 460 468 464 456 |
463 (46.5 HRC) |
| Wind turbine bolt (42CrMoA) |
338 328 331 346 344 |
337 (36.5 HRC) |
375 352 378 346 357 |
362 (39.0 HRC) |
| 321 311 326 326 314 |
320 (35.0 HRC) |
358 354 344 346 354 |
351 (38.0 HRC) |
|
| 366 346 352 375 362 |
360 (39.0 HRC) |
358 357 360 366 378 |
364 (39.5 HRC) |
|
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