Working condition requirements
It is required that the copper mould tube must have the characteristics of wear resistance, high temperature resistance, corrosion resistance, high strength, high hardness and good heat dissipation. Therefore, the copper tube is composed of bimetallic, the base layer is copper, and the inner layer is high-performance special metal coating (0.08-0.1 hard chromium or nickel alloy). However, the copper mould tube also has a service life, and it must be replaced after the inner layer is worn.
Coating material requirements
At present, Cr coating is generally used for copper tube coating, with high hardness (＞ hv600), but the thickness is relatively thin (0.06-0.12mm), and it is quickly worn out in use, and the wear resistance of Cr coating is limited. Although Ni, Ni Fe and Co Ni are lower than Cr coating, the thickness of the coating can be increased, so the wear resistance and service life of copper pipe can be improved.
| Combinatorial Materials | Hardness, HV | CTE（*10-6/°C） | Thermal conductivity
W/（m. K） |
| Cr | ≥600 | 7 | 60-66 |
| Ni | ≥140 | 14-16.7 | 76-84 |
| Ni-Fe | ≥250 | 14 | 63-88 |
| Ni-Co | ≥280 | 14 | 75-84 |
| Co-Ni | ≥220 | 14 | 80-84 |