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TD Process

TD process produces high-functional coating formed from carbide including niobium, and chromium. In the process, the workpiece is dipped into the high-temperature salt bath to be coated uniformly. The coating is applicable to workpiece of complicated shape and achieves high hardness of Hv3200-3900. TD process is a vital technology and obtains good evaluation in mold production industry.

TD-VC coating

TD-VC coating

TD-VC coating is the extremely hard vanadium carbide(VC) coating produced by TD process, one of the high temperature salt bath treatments. The coating with cross-sectional hardness as high as Hv3,200 to 3,800, protects the workpiece surface from wearing and seizing. TD-VC coating, which improves the durability of workpieces very much, is highly evaluated as the excellent surface modification indispensable for the metal mold industry.
The salt bath treatment can produce uniform coating film even on a inside dead area regardless of the workpiece shape.

■Properties of TD-VC coating

Coating type Thickness(μm) Hardness(HV) Adherence mechanism
TD-VC 5〜15 3,200〜3,800 Diffusion type
Cr-plating 30〜50 900〜1,000 Mechanical type

■Cross sectional Structure of TD-VC coating

Cross sectional Structure of TD-VC coating

■Wear resistance by coining

Wear resistance by coining

■Molten aluminum resistance

Molten aluminum resistance

TBS-1500 coating

TBS-1500 coating

TBS-1500 coating is an iron-boride hard coating produced by the high temperature salt bath treatment as well as TD-VC coating. TBS-1500 exhibits unparalleled durability against erosion with high temperature particles. Materials to be processed are transition metals including iron, and the coating chemically reacts on the base metal to form boride compound on the processed material surface.Generally, TBS-1500 method can form thicker coating than TD-VC method.

■Cross sectional Structure of TBS-1500 coating

Cross sectional Structure of TBS-1500 coating

■Hardness and thickness of TBS-1500 coating by processed substrate

Kind of metals Coating hardness(Hv) TBS-1500 coating thickness(μm)
Austenite stainless steel SUS304 1,300〜1,700 5〜30
Alloy tool steel SKD61 1,300〜1,700 30〜100
Cr-Mo steel SCM435 1,300〜1,700 30〜100
Carbon steel for machine structure S45C 1,200〜1,500 30〜100
Rolled steel for general structure SS400 1,200〜1,500 30〜100
Bearing steel SUJ2 1,200〜1,500 30〜100

Coating Properties of TD-VC/TBS-1500

■Hardness and Thickness of TBS-1500

Coating Type TD-VC TBS-1500 Thermal CVD PVD Chrome Plating Nitriding
Coating Type VC Fe-B TiC, TiCN TiN, CrN Cr Fe-N
Coating Hardness(Hv) 3,200〜3,800 1,200〜1,700 2,300〜3,800 2,000〜2,300 900〜1,000 900〜1,000
Coating Thickness(μm) 3〜15 10〜100 3〜15 1〜5 20〜50 10〜20
Process Molten Salt Immersion Molten Salt Immersion Heating in Gas Discharge in Decompressed Nitrogen Gas Electrolysis of aqueous solution Molten Salt Immersion
Process Temperature(℃) 900〜1,000 900〜1,000 900〜1,000 400〜600 50〜80 500〜600
Distortion × × ×
Adhesion ×
Wear Resistance
Heat Resistance ×

■Hardness comparison at room temperature

Hardness comparison at room temperature

■Hardness comparison at high temperature

Hardness comparison at high temperature

Work Flow of TD Process

Work Flow of TD Process


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