JPS61106777A - Corrosion resistant cast product - Google Patents

Abstract

PURPOSE:The titled product superior in H2SO4 corrosion resistance and in which strain is scarcely caused, by composing Na2.nSiO2 glass layer on cast surface by burning and hardening said layer. CONSTITUTION:Cast product is Ni plated favorably to a prescribed thickness, further paint contg. Na2O.3SiO2-alpha-Al2O3-TiO2 is blown and coated thereon, then burnt at about 300 deg.C to undercoat Na2O.3SiO2 with Al2O3, etc., and these are hardened. Next, paint contg. Na2O.3SiO2 is coated at about 100 deg.C on the undercoat by spray gun, then the product is thrown into an air bath of about 100 deg.C, heated to about 200 deg.C by about 10 deg.C/min, held thereat for about 60min to burn and harden Na2O.3SiO2 glass layer dense, superior in H2SO4 corrosion resistance and adhesive property. Since the treating temp. is low, strain is scarcely caused in the obtd. titled product.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention provides a corrosion-resistant cast product with improved sulfuric acid corrosion resistance, for example, a superfluid casing for a marine diesel engine and a product using trap casting. It's about.

[Prior art and its problems]

For example, it has been proposed to apply nickel plating to the gauging of a crusher for a marine diesel engine to prevent corrosion caused by sulfuric acid.

One reason is that low-quality heavy oil with a content of 1,000,000 million yen is used as fuel for ships due to cost considerations, and because the exhaust gas is cooled with gold sea water or fresh water, it contains M. Sulfuric acid is produced from the sulfur content, and the surface of the casting is plated with nickel in order to prevent the sulfuric acid from attacking the surface of the casting.

However, even if nickel plating can increase the resistance to 6 injections, this durability is only about 3 years, so if it is used under normal conditions after nickel plating, Currently, the nickel plating process is performed again three years later.

At the same time, attempts were also made to slow down nickel plating reprocessing by increasing the thickness of the nickel plating, but
This simple technical idea does not provide a fundamental solution; in other words, even thicker nickel plating does not slow down reprocessing much.

[Disclosure of the invention]

In order to improve the sulfuric acid corrosion resistance of cast iron products, unexploded KY4@ is constructed by weathering the casting surface with an enamel protective film TG8, which improves the sulfuric acid corrosion resistance of the casting product. Notice that it is also significantly the same as above, for example bt0247%, B, 0.17%, N
A prototype was produced by baking and hardening a glass film having a composition of 24% A2U and 12% A12(J) around the surface of the casting.

Since this enamel protective film-baked structure and piece plate μ1 were superior in acid resistance, Hayabusa applied this technical concept to over-sweetened warguns for marine diesel engines.

My heart is in the process of developing this technology, and it is predicted that it will be banned.
0 defects were buried, 510247%
, B2 (J317%%Na2024%, Al, 0312
A glass film with a composition of 29% was installed in a casing for a marine diesel engine, and the v′i distortion occurred, and the casing thickness of 7% was distorted.29 This German enamel protective film composition concept When applied to turbocharger case songs for diesel engines, it has the same advantages as sulfuric acid corrosion resistance, but
*The shortcoming of the V thickness is something that cannot be adopted in the current VN1.However, the present inventor believes that the effects of the enamel protective film on the resistance, and the effectiveness of the same as above are attractive. Further research? Why does the above defect occur?It is clear that the heat treatment temperature during baking of hollow wax is the biggest cause. Since the leopard is a 650 to 70 C animal, this = 5 still temperature treatment t'il+ causes casting YC distortion. It has now been discovered that products based on dead lees rice are superior to the corrosive properties of sulfuric acid, and there is almost no deformation of diseased products even after baking treatment.0 [Example] In castings A thick nickel plating is applied to the exhaust/air passage surface V of the exhaust/air passage gauging for diesel engines with structure fj, δn, and Na2U/3S10□ is applied on the nickel plated surface.
2Q M i 'ftf5, a-A right Us75'JI
L Jt fls, Tiez;l)
``J Shoulder - Science Q Spray V-Gun and spray value long, after 7 IL
Pour into the air tank of JfJ'C, heat up at 0°C/min for 3t), set and hold at 1300°C for 30 minutes.

After the formation of a phosphorescent compound formed by the reaction between this Na, Q・n5to2 and a coating agent such as alumina, Na2 (J-3SiO2 rich paint 1f Jiuo
Pour the iron into a tube at °C, then put it into an air path at 100 °C, heat it at 200 °C at a rate of fJlO °C/min, and then strain it at 21)t)'C for 60 minutes. Hold it.

When compared to the above example, a porous layer with high heat resistance, although slightly inferior in corrosion resistance, is formed on the nickel plating layer on the surface of the casting at the exhaust route of the over-concile casing. On top of this layer, a fine layer with a thickness of about 1 μm and highly resistant to VL is formed, and the corrosion resistance of this joint passageway is extremely excellent. Monodoritsu 7
child. ' Also, the above protective film μ is made of a glass material, and the sulfuric acid corrosion resistance is as expected. The 7L was unusual in that it produced almost no distortion, which was unexpectedly thick in the past. In other words, the Na2S/Sin and glass films were hardened by baking, and the t1 supercharging cycle was low at a low FL7j.

δ et al., this protective film had excellent adhesion, and there was no fear of the protective film peeling off, and it was extremely durable. Toe 9: Since the thermal expansion coefficients of the protective film and the nickel plating layer are about the same, the protective film was often cracked and peeled off due to uneven dust on the desk board.

Also, if the casing has Na2O/n5i (J Unfortunately, if you use a convenient material, you won't have the problem of corrosion due to cavitation. It can effectively prevent the disease caused by protective gland formation.

Claims (1)

[Claims] A corrosion-resistant cast product made by baking and hardening a Na_2O/nSiO_2 glass layer on the surface of the casting.