JPH10328881A - Covered electrode - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a covered electrode for underwater welding and for non- hygroscopic land use, which are each easily manufactured and have hygroscopicity applying a hydrophobic treatment to the surface of the covered part and specifying the angle of contact with water. SOLUTION: As the hydrophobic treatment, the surface of a covered electrode is coated with a slurry hydrophobic processing agent in which, for example, hydrophobic inorganic oxide particles or hydrophobic organic tetrafluoroethylene particles and a resin are mixed and dispersed in a solvent. The angle of contact with water is not less than 90 deg. on the hydrophobic-treated surface of the covered electrode. Welding using such covered electrode 1 is carried out while an arc is generated between the tip end of the electrode 1 and a base metal 2 to form a molten pool 6 on the base metal 2. At the tip end of the electrode 1, the tip end of a metallic core wire 1a for generating an arc is always recessed from that of the cover material 1b, whose cylindrical tip end serves as a protective tube, protecting the arc from surrounding water 5 by means of a gas generating through thermal decomposition.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to marine structures such as oil production facilities, cargo handling facilities, storage facilities, offshore airports, marine storage bases, bridges / submerged tunnels, wave power / tidal current / temperature difference power generation facilities, marine ranches, etc. Welded underwater welding rods for offshore joining, underwater repair and maintenance, and coated welding rods used for welding steel structures such as ships and bridges on land.
The present invention relates to a coated welding rod when it is required to be used in a humid place or to be installed in light rain.

[0002]

2. Description of the Related Art As a commercially available coated welding rod for wet-type underwater welding, there is a commercially available product in which an outer surface of a coating material is plated with copper and waterproofed. In the case of ordinary underwater repair work, there are many cases in which vinyl tape is wrapped around the outer surface of a commercially available welding rod used on land to be easily waterproofed.

[0003] Although not for underwater welding, a coated welding rod having a water-repellent property for use in atmospheric welding is disclosed in Japanese Unexamined Patent Publication No. Hei.
No. 2,330,933. This is a non-low coating material comprising 0.05 to 0.20% by weight of silicone and the remainder consisting of a coating comprising an arc stabilizer, a slag forming agent, a deoxidizing agent, an organic substance and a fixing agent. This is a hydrogen-coated welding rod.

[0004]

The above prior art has the following problems. (1) A coated welding rod which is copper-plated and waterproofed is expensive, and if a copper plating film is damaged, it absorbs moisture therefrom and the plating effect is lost.

(2) When vinyl tape is wrapped around a commercially available coated welding rod, the welding worker dives for a long time to store the welding rod in water, or removes the welding rod from a storage box or attaches it to a welding holder. At this time, water may enter the welding rod from a gap between the tapes, or the tape may be damaged and may absorb moisture.

(3) A non-low hydrogen coated welding rod having a coating agent containing silicone is a special coated welding rod added in the manufacturing process of the welding rod, and partially absorbs moisture in water. Can not. Also, this coated welding rod
It can be used to some extent in humid places, but because it is not completely water-repellent, it partially absorbs moisture when wet with rain,
It cannot be used without drying treatment.

[0007] In order to solve the above-mentioned problems, the present invention provides a coated welding rod for underwater welding and a land coated welding rod which does not absorb moisture, which is easily manufactured and has water repellency by subjecting the coated welding rod to a hydrophobic treatment. The purpose is to obtain.

[0008]

As the coated welding rod for wet type underwater welding and the land-based welding rod that does not absorb moisture, it is most effective to use a commercially available coated welding rod used in the atmosphere after waterproofing. From this perspective, the following was developed.

The coated welding rod of the present invention is obtained by making the surface of the coated portion hydrophobic so as to have a water repellency having a contact angle with water of 90 ° or more.

[0010] As the hydrophobic treatment method, for example, a slurry-like hydrophobic treatment agent obtained by mixing and dispersing hydrophobic inorganic oxide particles or tetrafluoroethylene particles as a hydrophobic organic substance and a resin in a solvent is used. Using a method of coating the coating surface of the coating welding rod, or coating the coating surface with a so-called silane compound such as alkoxysilane, chlorosilane, or silazane having a hydrophobic group, dimethylpolysiloxane, or titanate coupling having a hydrophobic group. And a method of treating with a solution of an aluminum-based coupling agent to bind a hydrophobic group to the surface of the covering portion.

As the hydrophobic inorganic oxide particles used for the coating, ceramic particles such as silica, alumina and titanium oxide and iron oxide particles are used, and the particles obtained by treating the particles with a surface treating agent having a hydrophobic group are used. At least one
Use seeds.

The size of the inorganic oxide particles is from 0.001 to
100 μm is preferred. If the size of the particles is less than 0.001 μm, it becomes difficult to handle when making the hydrophobizing agent, and
If it exceeds μm, impregnation of pores formed in the coating portion of the welding rod becomes insufficient.

The surface treating agent having a hydrophobic group includes silane, chlorosilane, and the like having an alkyl group or a fluorine-substituted hydrophobic group.
So-called silane compounds of silazane, dimethylpolysiloxane, titanate coupling agents having an alkyl group, and aluminum-based coupling agents are used. However,
The method is not limited to the above-mentioned method as long as the method can render the inorganic oxide particles hydrophobic.

As the silane compound having an alkyl group,
Those having a methyl group, for example, methylmethoxysilane CH ₃ Si (OCH ₃ ) ₃ , dimethyldimethoxysilane (CH
₃ ) ₂ Si (OCH ₃ ) ₂ , trimethylmethoxysilane (CH ₃ )
₃ Si (OCH ₃ ), methyl triethoxysilane CH ₃ Si
(OC ₂ H ₅ ) ₃ , dimethyldiethoxysilane (CH ₃ ) ₂ Si
(OC ₂ H ₅ ) ₂ , trimethylethoxysilane (CH ₃ ) ₃ Si
(OC ₂ H _5), include hexamethyldisilazane, it is one having an ethyl group, ethyltrimethoxysilane C ₂
H ₅ Si (OCH ₃ ) ₃ , diethyldimethoxysilane (C
_{2 H 5) 2 Si (OCH} 3) 2, triethyl silane (C _{2
H 5) 3 Si (OCH 3} ), ethyl triethoxysilane C ₂ H ₅
Si (OC ₂ H ₅ ) ₃ , dimethyldiethoxysilane (C ₂ H ₅ ) ₂
Si (OC ₂ H ₅ ) ₂ , triethylethoxysilane (C ₂ H ₅ ) ₃
Si (OC ₂ H ₅ ) and the like having a propyl group, and propyltrimethoxysilane C ₃ H ₇ Si (OC
H ₃ ) ₃ , dipropyldimethoxysilane (C ₃ H ₇ ) ₂ Si (O
CH ₃ ) ₂ , tripropylmethoxysilane (C ₃ H ₇ ) ₃ Si
(OCH ₃ ), propyltriethoxysilane C ₃ H ₇ Si (O
C ₂ H ₅ ) ₃ , dipropyldiethoxysilane (C ₃ H ₇ ) ₂ Si
(OC ₂ H ₅ ) ₂ , tripropylethoxysilane (C ₃ H ₇ ) ₃
Si (OC ₂ H ₅ ) and the like, and n-octadecyltrimethoxysilane, n-dodecyltriethoxysilane and the like as long-chain alkylsilanes.

The above-mentioned alkoxysilane having 1 to 3 alkyl groups having 1 to 20 carbon atoms can be used alone or as a mixture of a plurality of chlorosilanes or silazanes. However, the metal alkoxide of the present invention is not limited to the above exemplified compounds (the same applies hereinafter).

Examples of the silane compound having a fluorine-substituted hydrophobic group include perfluorooctylethyltriethoxysilane CF ₃ (CF ₂ ) ₇ (CH ₂ ) ₂ Si (OC ₂ H ₅ ) ₃ and perfluoroisopropylethyltriethoxy silane (CF ₃ ) ₂ C
In addition to F (CH ₂ ) ₂ Si (OC ₂ H ₅ ) _{3 and the} like, perfluoromethylethyltrimethoxysilane, perfluorobutylethyltrimethoxysilane, perfluorooctylethyltrimethoxysilane, perfluorooctylethylmethyldimethoxysilane And alkoxysilane having a perfluoroalkyl group having 1 to 20 carbon atoms, preferably 1 to 10 carbon atoms.

As the titanate coupling agent, isopropyl triisostearoyl titanate, isopropyl tris (dioctyl pyrophosphate) titanate,
Examples thereof include tetraisopropyl bis (dioctyl phosphite) titanate and tetraoctyl bis (ditridecyl phosphite) titanate.

Examples of the aluminum-based coupling agent include acetoalkoxyaluminum diisopropylate.

Tetrafluoroethylene particles are also suitable as hydrophobic particles. The above-mentioned hydrophobic inorganic oxide particles and tetrafluoroethylene particles can be used alone or in combination.

As a method for coating the surface of the coating portion of the welding rod with the slurry-like hydrophobizing agent in which the hydrophobic particles, the resin, and the solvent are mixed, usual methods such as spraying, brushing, and dipping can be used.

The mixing ratio of the hydrophobic particles to the resin is preferably from 100: 0 to 10:90 by weight, but the contact angle of water on the coating after the hydrophobizing treatment is not less than 90 °, and is not necessarily required. It is not limited to this range.

The coated welding rod that has been subjected to the above treatment has a property of being completely or almost not wetted by water. When submerged in water, it has the property of forming a thin film of air on the surface. This air film can be confirmed by being reflected in silver when exposed to light. In addition, since the inside of the coating has been subjected to the water repellent treatment, even if it is immersed in water, there is no intrusion of water into the inside and it is not completely wetted with water. be able to.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION The surface of various coated welding rods of illuminite, lime, titania, and titanium oxide, which are commercially available welding rods often used for underwater welding, are subjected to a hydrophobic treatment.
The coating was provided with water repellency.

The following three types of hydrophobizing agents (A, B,
C) was used. Hydrophobizing agent A: Silica particles whose surface has been hydrophobized with trimethylmethoxysilane as hydrophobic particles (SiO ₂ :
A slurry prepared by mixing 50 parts by weight of 99% and a particle size of 2 μm), 50 parts by weight of a resin (room-temperature-curable silicone resin, solid content: 20%), and 200 parts by weight of isopropyl alcohol as a solvent; -A mixed solution of 20 parts by weight of octadecyltrimethoxysilane and 80 parts by weight of n-hexane Hydrophobizing agent C: 60 parts by weight of tetrafluoroethylene fine particles (particle size: 5 m) as hydrophobic particles, and bisphenol A type as a resin Epoxy resin (ThreeBond) 40
A slurry in which 200 parts by weight of toluene as a solvent is mixed with parts by weight.

Various illuminite-based, lime-titania-based, and titanium oxide-based coated welding rods were immersed in each of the hydrophobizing agents A, B, and C for 1 minute, and then dried at 50 ° C. for 24 hours.

The contact angle of water on the surface of each of the coated welding rods subjected to the hydrophobizing treatment is about 160 degrees for the hydrophobizing agent A and about 140 degrees for the hydrophobizing agent B. In the case of C, it was about 160 degrees.

An underwater immersion test was performed in which various coated welding rods treated with the hydrophobizing agents A, B, and C were left in water for 7 days. When the weight of the coated welding rod before and after the test was measured for each welding rod, there was no change in weight. Therefore, each coated welding rod did not absorb moisture. When the coating was peeled off from the coating welding rod and examined, it was found that the hydrophobizing agent had penetrated into the coating from the surface of the coating. Therefore, even if the coating surface was slightly scratched, the water repellency of the coating was not lost.

Next, an underwater welding test was performed at a water depth of 30 cm using various types of coated welding rods treated with the hydrophobizing agents A, B, and C. When placed in water, a film of air formed on the surface. FIG. 1 is a diagram schematically showing underwater welding with a covered welding rod. The welding is performed in a state where the coated welding rod 1 is inclined forward in the traveling direction while an arc is generated between the tip of the coated welding rod 1 and the base material 2 to form a molten pool 6 on the base material 2. .
At the tip of the welding rod 1, a metal core wire 1a that generates an arc 3
Of the coating 1b is always deeper than the tip of the coating 1b, and the cylindrical tip of the coating 1b serves as a protective tube,
The arc 3 is protected from surrounding water 5 by the gas 4 generated by the thermal decomposition of b. Thus, stable welding can be performed.
The weld metal 7 formed on the base material 2 is protected by slag 8 generated by melting the component of the coating material 1b. The gas 4 surrounding the arc 3 pushes out water that is about to enter from the surroundings and floats as bubbles 9.

If the coating 1b is not hydrophobized, the coating 1
When b absorbs moisture and falls off, the protective cylinder at the tip of the coating 1b disappears, so that the gas 4 atmosphere surrounding the arc 3 is not formed, and the arc directly contacts water and becomes unstable. In addition, due to the falling off of the coating 1b, the welding metal 7 is not protected by the slag 8, and welding defects such as welding and blow holes due to oxidation and rapid cooling of the welding metal occur frequently. Further, when the coating material 1b absorbs moisture, hydrogen gas thermally decomposed by the arc 3 is generated in the gas 4 for protecting the arc 3, so that the absorbed moisture causes welding defects such as blow holes.

The results of the underwater welding test using the coated welding rod of the present invention that has been subjected to the hydrophobizing treatment show that various types of coated welding rods (illuminite, lime) treated with the hydrophobizing agents A, B, and C were used. Regardless of which of the titania-based and the titanium oxide-based was used, the welding was stable, and no defect was observed in the welded portion.

After the coated welding rod of the present invention was immersed in water, taken out of the water and blown with compressed air, welding was performed. As a result, the welding was stable, and the results of X-ray inspection of the welded portion were good and sound. Successful welding.

Therefore, the coated welding rod of the present invention has a moisture absorption resistance and can be used not only in water but also on land. Even when welding on land, the moisture absorption of the coating material causes welding defects such as blowholes and hydrogen cracking, so the control of coated welding rods is strict.When welding high-grade materials such as high-tensile steel, Is to be dried in a drying furnace to remove water. Therefore, if the coated welding rod which has been subjected to the water-repellent treatment as in the present invention does not absorb moisture, it is easy to manage the coated welding rod and welding at a particularly high temperature place (for example, in a ballast tank of a ship or at sea It can also be used for welding in

[0033]

According to the present invention, the coated welding rod is subjected to a hydrophobizing treatment on the surface of the coated welding rod, for example, by immersing a commercially available coated welding rod in a hydrophobizing agent, whereby the coated material is made water-repellent. Therefore, it can be easily manufactured, is suitable for mass production, and is inexpensive.

Further, since the hydrophobizing agent enters the inside of the porous coating material, even if the coating surface is damaged, the water repellency is not lost, and the durability in the underwater operation and the land operation where moisture absorption is a problem is excellent. .

[Brief description of the drawings]

FIG. 1 is a schematic diagram illustrating an underwater welding method using a covered welding rod.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Coated welding rod 2 Metal core wire 3 Coating 4 Thermal decomposition gas of coating material 5 Water 6 Weld pool 7 Weld metal 8 Slag

Claims (5)

[Claims] 1. A coating characterized in that a surface of a coated welding rod in which a metal core wire is wrapped by a coating material is subjected to a hydrophobic treatment, and the coating material is provided with water repellency having a contact angle with water of 90 ° or more. Welding rods. 2. The coating according to claim 1, wherein the treatment agent used for the hydrophobic treatment comprises a slurry in which hydrophobic particles and a resin are mixed and dispersed in a solvent, and the slurry is coated on the surface of the coating material. Welding rods. 3. The method according to claim 1, wherein the hydrophobic particles form a surface of the inorganic oxide particles.
The coated welding rod according to claim 2, which is a particle produced by treating with a surface treating agent having a hydrophobic group. 4. The coated welding rod according to claim 3, wherein the hydrophobic particles are made of silica, and the surface treating agent having a hydrophobic group is a silane compound. 5. The coated welding rod according to claim 2, wherein the hydrophobic particles are polytetrafluoroethylene particles that are organic substances.