Low-temperature high-speed solid-powder chromium-impregnation method under action of direct current field

Abstract

The invention discloses a low-temperature high-speed solid-powder chromium-impregnation method under the action of a direct current field, which relates to the technical field of chemical heat treatment of metal surfaces. The method comprises the following steps: putting a platelike electrode in a solid-powder chromium-impregnation agent; using the platelike electrode as the positive electrode anda chromium-impregnation part as the negative electrode, and connecting the two electrodes in parallel to the positive electrode and the negative electrode of a direct current power supply of which the voltage can be continuously adjusted within the range of 5-100V; sealing the platelike electrode, the chromium-impregnation part and the chromium-impregnation agent in an impregnation tank; heatingthe impregnation tank at 600-900 DEG C; and when the furnace temperature reaches the set value, applying a voltage of 5-100V between the two electrodes to carry out the chromium-impregnation on the chromium-impregnation part. The method uses the impregnation agent which is same as that of the prior traditional solid-powder chromium-impregnation and can obtain the same chromium-impregnation thickness as common chromium-impregnation by using low-temperature heating and short-time heat preservation. When the same heating temperature and heat preservation time as common chromium-impregnation are used, the thickness of the chromium-impregnation layer can be increased by 3-8 times so as to save the energy and reduce the production cost.

Description

technical field [0001] The invention relates to the technical field of metal surface chemical heat treatment, in particular to a low-temperature rapid solid powder chromizing process under the action of a direct current electric field, which can significantly improve the oxidation resistance, corrosion resistance and wear resistance of metal parts under strong wear conditions and in corrosive media after chromizing performance loss. Background technique [0002] The chromizing process is at high temperature, through the surface absorption of active chromium and the mutual diffusion of chromium, iron and carbon, to form a solid alloy layer of iron, chromium and carbon on the surface of the workpiece. This carbon-chromium compound layer has good wear resistance, high-temperature oxidation resistance, and thermal fatigue resistance, and has a high resistance in the atmosphere, tap water, steam and oil, hydrogen sulfide, nitric acid, sulfuric acid, alkali, and sodium chloride aq...

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Problems solved by technology

The above two methods can reduce the powder chromizing temperature and reduce the holding time, but the process operation is relatively complicated, and some parts are not suitable for long-term mechanical vibration during the process

[0007] Since the generation of active chromium atoms in the current solid powder chromizing is due to the thermal decomposition of the infiltrating agent under the action of high temperature, its concentration is directly related to the chromizing temperature, the content of chromium donor and activator in the infiltrating agent, etc. Diffusion on the surface of parts also mainly depends on the effect of temperature, and the probability of diffusion movement to all places is the same, so a considerable amount of active chromium atoms infiltrate into the inner wall of the infiltration box and the non-working surface of parts during chromizing, causing a lot of waste , so there are disadvantages such as high processing temperature, long processing time, low utilization rate of penetrating agent, high cost, etc.

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