JPH0353388B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a surface treatment method that is applied to provide high wear resistance to sliding surfaces of engine valve cams, for example, as a workpiece. Conventionally, as a method of this type, a method is known in which a plasma arc generates a molten part on the surface of a workpiece made of cast iron or other metal material, and then the molten part is cooled and solidified to form a remelt treatment layer. In such a case, the treated layer is merely obtained as a hardened layer of the chill structure by increasing the cooling rate during the cooling solidification, and thus, for example, in the case of the above-mentioned valve train cam, the treatment layer is not necessarily sufficient for this purpose. It is accompanied by disadvantages that are difficult to obtain in terms of wear resistance. Conventionally, members with wear resistance and galling resistance on sliding surfaces have been manufactured by mixing base metal powder and sulfide powder using powder metallurgy, compacting the mixture, and sintering it. There is a method in which sulfide powder is added to molten metal and stirred and then cast, but this is disadvantageous in terms of cost because expensive sulfide is mixed into unnecessary parts. In addition, during sintering in the powder metallurgy method, and during pouring and solidification in the casting method, sulfides are held at high temperatures for a relatively long period of time, so they decompose and the amount remaining as sulfides is significantly reduced. As a result, sufficient wear resistance,
It was difficult to obtain a material with galling resistance. The object of the present invention is to provide a method for obtaining a surface treatment layer that further improves various properties of the remelt treatment layer, such as wear resistance, without such conventional disadvantages. A remelt treatment layer in which a plasma arc creates a molten part on the surface of a workpiece made of a metal material, and an additive made of a metal material or other material different from the metal material of the workpiece is mixed into the molten part, and the mixture is cooled and solidified. In the method of forming a shielding gas flow of the plasma arc, the alloy or compound containing the additive is forcibly mixed into the molten zone along with the plasma arc, and the alloy or compound containing the additive is mixed into the molten zone. It is characterized by being formed. In this case, the additives include, for example, Ni, Cr, Mo and other metals or their alloys, WC, SiC, MO ₂ C,
Cr ₃ C ₂ , B ₄ C and other carbides, BN, TiB and other borides, MoS ₂ , WS ₂ , FeS and other sulfides,
It consists of at least one type of powder selected from Al ₂ O ₃ , SiO ₂ and other oxides. The method of the present invention will be explained in more detail with reference to the accompanying drawings.
Reference numeral 1 indicates a valve train cam and other workpieces made of cast iron, aluminum alloy, or other metal materials, and 2 indicates a plasma torch that opposes this, and the torch 2 has a central electrode 3 and its outer periphery, as shown in FIG. The nozzle 5 is provided with a nozzle 5 via a working gas passage 4, and a shield cap 7 is provided on the outer periphery of the nozzle 5 via a shield gas passage 6. At the tip of the nozzle 5, a plasma gas passage 8 connected to the working gas passage 4 is provided. A cooling water passage 9 is provided in the nozzle 5, and the plasma gas passage 8 is provided with a cooling water passage 9.
A jet of plasma gas is blown onto the workpiece 1 through the jet, and a plasma arc 10 is applied between the workpiece 1 and the electrode 3 to form a molten part 11 on the surface of the workpiece 1. Thus, when the torch 2 is scanned over the workpiece 1, the molten area 11 is gradually and continuously formed on the scanning line, and this is gradually cooled and solidified from the starting side, forming a so-called remelt treatment layer. This is not particularly different from the conventional method. According to the present invention, as described above, a powder of a material different from the metal material of the workpiece 1 is prepared as the additive 12, and is guided into the molten part 11 along with the plasma arc 10 and inside the melted part 11. For example, as shown in FIG. 1, a mixing tube 13 made of ceramic, for example, is prepared with its tip facing the plasma arc 10, and the additive 12 is mixed into the mixing tube 13 forcibly. For example, by transporting argon gas, the inside of the mixing tube 13 is supplied into the arc 10, so that the additive 12 is guided to the melting part 11 along with the arc 10 and mixed therein. I made it. To explain further, the flow rate of the plasma jet in the plasma torch 2 is set to 20
m/sec, the flow velocity of the shielding gas around the outer circumference is 0.33
m/sec, and the conveyance speed of the powder is set to 1.5 to 3 times or more than the flow rate of the shielding gas, for example 7 m/sec, so that the powder overcomes the shielding gas flow and is guided into the plasma jet. I did it like that. The operating states of the method of the present invention are, for example, as shown in FIGS. 2 to 6, that is, first, as shown in FIG. 2, the plasma arc 10 is generated between the plasma torch 2 and the workpiece 1. There is a third on the workpiece 1 side.
While the melting zone 11 is generated as shown in the figure, the additive 12 is conveyed through the introduction pipe 13 by, for example, argon gas, and thus the additive 12 is transferred to the plasma as shown in the fourth figure. arc 10
The arc 1 is introduced into the upstream side of the arc 1 and heated and accelerated.
0 and is introduced into the melting section 11 and mixed therein. At this time, the plasma torch 2 is scanned in the lateral direction, and the molten part 11 gradually expands in the lateral direction, as shown in FIG. The molten metal is solidified to form the above-mentioned remelt treatment layer 11a. During such operation, each molten part 11 is given a stirring action by causing the molten metal to flow in the vertical and lateral directions. The additive 12 introduced therein is almost uniformly dispersed inside this by the stirring action, resulting in a remelt treated layer 11a.
For example, as shown in FIG. 6, the additive 12 is almost uniformly dispersed inside the treated layer, and the corresponding properties, such as wear resistance, of the treated layer are improved by the additive 12. The gas amount of the plasma jet in the plasma arc 10 is set to be a small amount, for example, 0.3 to 3.0/min, compared to the case of normal plasma melting, and the conveyance speed of the additive 12 is, for example, 0.5 m/sec or more. Further, the current and voltage of the arc 10 are, for example, 30 to 200 A and 20 to 30 V, and the size of the powder of the additive 12 is generally 200 μ or less, particularly,
100μ is preferred. It should be noted that when the additive 12 is mixed into the melting section 11, it is dispersed in the powder state as it is, or at least a part of it is melted or heat-dissipated and the additive 12 is mixed into the melting section 11.
The alloy or compound shall be made within. Example 1 A workpiece 1 consisting of an FC30 Okoshi wear test piece was processed using the conditions shown in the first diagram. The plasma current was set to 50 A, the flow rate of plasma gas was set to 0.8/min, and the scanning speed of the plasma torch was set to 0.5 m/min to form a remelt treatment layer on the entire surface, and Cr powder was mixed therein as additive 12. The size of Cr powder is 5 to 100μ, and the feeding rate is 0.2g/min.
And so. The remelt treated layer was formed at a depth of 1.8 mm from the surface and exhibited a chilled composition due to rapid cooling during cooling and solidification. Cr was contained in the layer in a substantially uniformly dispersed manner at a ratio of about 1.2% over the entire area. The resulting product was designated as A and the product with a simple remelt treatment layer was designated as B. The results of the abrasion test are as follows. Co% Specific wear A 1.2 8.6×10 ^-8 mm ² /Kg B 0 2.2×10 ^-7 The rotor used in this test was carburized and quenched SCM420, and then hard chrome plated to a thickness of 80μ. The wear rate was 1.36m/sec, the final load was 3.1Kg, and the friction distance was 200m. Example 2 Using the apparatus shown in the first figure, a workpiece 1 consisting of an S50C Okoshi type wear test piece was processed. The entire surface of the specimen was treated with a plasma current of 100 A, a plasma gas amount of 0.8/min, and a plasma torch scanning speed of 0.5 m/min, and Mo ₂ C was added as additive 12 to this.
powder was added. The size was 2 to 30μ, and the conveyance amount was 0.6g/min. The remelt is 1.2 from the surface.
It occurred at a depth of mm and exhibited a martensitic structure. Mo was contained in the remelt treated layer in a substantially uniformly dispersed manner at a ratio of about 3.6% over the entire area. The obtained product was designated as C, and the product with a simple remelt treatment layer was designated as D. The results of the abrasion test are as follows. Mo% Specific wear amount C 5.2 7.8×10 ^-7 mm ² /Kg D 0 8.5×10 ^-6 〃 Example 3 Using the apparatus shown in Fig. 1, an Okoshi type wear test piece of Ni-10% Cu alloy was used. Work 1 was processed. Plasma current 100A, plasma gas 0.8/min,
TiB with additive 12 was scanned over the entire surface at a scanning speed of 0.5 m/min with the plasma torch.
powder was added. This supply amount was set to 0.4 g/min. The treated layer is formed at a depth of 1.0 mm, and inside this
TiB was almost evenly distributed over the entire area at a volume ratio of approximately 2.6%. The results of a comparison between the product designated as E and the product subjected to simple remelting treatment as F are as follows. TiB% Specific wear amount E 2.6 4.0×10 ^-6 mm ² /Kg F 0 7.2×10 ^-6 〃 Example 4 Using the apparatus shown in Figure 1, workpiece 1 consisting of an FC30 Okoshi type wear test piece was treated. provided. The plasma current was 50 A, the plasma gas was 0.8/min, the scanning speed of the plasma torch was 0.5 m/min, and the entire surface was remelted and FeS powder was mixed therein.
The powder has a size of 5 to 30μ, and the amount of conveyance is
It was set to 0.3g/min. The treated layer was formed to a depth of 1.6 mm and exhibited a chilled structure, but there were
(FeMn)S, which is generated by the reaction between FeS, a part of FeS, and the base alloy Mn, has a volume ratio of approximately 20 over the entire area.
It was contained in a substantially uniformly dispersed proportion. The results of the abrasion test, with the product designated as G and the product subjected to simple remelting treatment as H, are as follows. (FeMn) S% Specific wear amount G 2.0 6.9×10 ^-8 mm ² /Kg H 0 2.2×10 ^-7 〃 Example 5 Using the apparatus shown in Figure 1, Okoshi type wear test pieces were made of Ai alloy AC2B. Work 1 was processed. Plasma current 100A, plasma gas amount 0.8/min,
The scanning speed of the plasma torch was 0.8 m/min,
The entire surface was remelted and Al ₂ O ₃ powder was added thereto. The powder had a size of 0.5 to 10 microns, and its conveyance rate was 0.6 g/min. The treated layer is formed to a depth of 0.8 m/m, and inside it, Al ₂ O ₃ is distributed over the entire area at a concentration of approximately 6.0 m/m.
It was contained in a substantially uniformly dispersed proportion. The obtained product was designated as I, and the product simply remelted was designated as J. The results of a comparative test are as follows. Al ₂ O ₃ % Specific wear amount I 6.0 8.3×10 ^-6 mm ² /Kg J 0 6.2×10 ^-5 As seen in each of the above examples, each workpiece 1 has improved wear resistance by mixing additives. Significantly improved. Example 6 Using the state shown in the first figure, a workpiece 1 for a stator consisting of a cast iron FC30 Okoshi type wear test piece was remelted as follows. i.e. plasma arc current
80A, plasma gas amount 0.8/min, plasma torch scanning speed 0.3m/min, remelt the sliding surface while drawing a trajectory, and apply 2μ to 10μ
Or ₂ S ₃ powder was contained in Ar gas at 1.2 g/min and supplied to the melting section. It melts to a depth of 1.2 mm from the surface, and the added Cr ₂ S ₃ reacts with the base metal Fe and its alloying element Mn, forming (CrFe) ₂ S ₃ ,
A dispersed structure containing a mixture of Cr sulfides such as (CrFeMn) ₂ S ₃ , (CrFe) ₃ S ₄ and (CrFeMn) ₃ S ₄ was formed.
The volume ratio of this Cr sulfide was 7.5%. these
The size of the Cr sulfide particles was about 1-8μ.
In this case, cooling after melting was heated by the base material other than the molten layer and solidified rapidly, leading to the precipitation of ledebrite and a so-called chill structure, in which (CrFe) ₂ S ₃ , (CrFe) ₃ S ₄ , (CrFeMn) ₂ S ₃ ,
(CrFeMn) ₃ S ₄ is dispersed. After the treatment, the sliding surface was polished to obtain a test piece K. For comparison, a chilled structure was formed by melting and hardening simply by plasma arc without adding Cr ₂ S ₃ powder. The sliding surface was polished and used as a test piece. These were subjected to wear tests in the same manner as in Example 1. The results are shown in the table below. Dispersed sulfide Volume ratio Specific wear amount K Cr sulfide 7.5% 8.0×10 ^-9 mm/Kg L − − 2.2×10 ⁻⁷ mm/Kg Example 7 Using the apparatus shown in Figure 1, iron and carbon = original Work 1 made of alloy (0.50%) was remelted as follows. That is, the plasma arc current is 80 A, the plasma arc Ar gas amount is 1/min, the plasma torch meandering scanning speed is 0.3 m/min, and the sliding surface is remelted while meandering.
A mixed powder of 50 wt% Cr ₃ C ₂ and 50 wt % MoS ₂ of 5 to 60μ is contained in Ar gas at 0.1 g/min, and is supplied to the melting zone to a depth of 1.4 m/m from the surface. As a result of the reaction between these mixed powders, a dispersed structure containing chromium sulfide particles of Cr ₂ S ₃ and Cr ₃ S ₄ was formed. The volume ratio of Cr sulfide was about 0.5%, and the particle size was about 1 to 9 μm. The treated surface of this product was polished to obtain a test piece M. For comparison, a test piece N which was remelted without any additives was prepared and subjected to the wear test in the same manner as in Example 1. The results are shown in the table below. Test piece Dispersed material Volume ratio Specific wearability M Cr sulfide 0.5% 3.6×10 ^-6 mm ² /Kg N None - 8.5×10 ^-6 mm ² /Kg Example 8 Using the apparatus shown in the first diagram, A cam lift part of an FC30 camshaft to be incorporated into an automobile engine was used as work 1 and was remelted as follows. That is, plasma arc current 60A, for arc
Ar gas amount 0.5/min, plasma torch scanning speed 1m/min, CrS ₃ powder supply amount of 2μ to 10μ 0.6g/
min, and the powder was fed into the melt bed. In this way, a cooling hardened layer with a thickness of 1.8 m/m containing various Cr sulfide powders of (CrFe) ₂ S ₃ , (CrFeMn) ₂ S ₃ , (CrFe) ₃ S ₄ and (CrFeMn) ₃ S ₄ was obtained. Ta. The volume ratio of Cr sulfide was 2.2%, and the particle size was 1 to 8μ.
The hardness was HRC58. The cam surface of this camshaft was polished and subjected to a practical test, and this was designated as test material 0. A camshaft made of one material in one direction was subjected to plasma treatment under the same conditions as above without adding the powder, and was then remelted and hardened, which was designated as camshaft test material P. The thickness of the hardened layer was 1.9 m/m, and the hardness was HRC51. Practical test conditions: Engine rotation: 1000 rpm Oil temperature: 65°C Test time: 200 hours As a result of this test, the amount of wear on the cam top of test material 0 was 10μ. The amount of wear on the cam top of test material P was 120μ. Example 9 Using the apparatus shown in Figure 1, the workpiece 1 was a valve blocker arm made of SCM420 to be incorporated into an automobile engine, and its slipper surface was remelted as follows. That is, arc current 45A, Ar gas amount for plasma arc 0.5/min, Cr ₂ S ₃ powder supply amount of 2-10μ 0.4g/min, torch speed 0.8m/min.
The surface of the slipper was melted in a locus, and the powder was added to the molten layer. As a result, Cr ₂ S ₃ was generated by the reaction between Fe, which is the main component of the base metal, and Mn, which is its alloying element. (CrFe) ₂ S ₃ , (CrFeMn) ₂ S ₃ ,
A chill hardened layer containing dispersed particles of Cr sulfide in which (CrFe) ₃ S ₄ and (CrFeMn) ₃ S ₄ were mixed was obtained. The thickness of that layer is 1.0mm, and the volume ratio of its Cr sulfide is 3.4
It was %. This was carburized and quenched and then polished to give a test material Q. On the other hand, a valve rocker arm made of the same material was simply carburized and quenched without being remelted and hardened using a plasma arc, and both test materials were subjected to the following practical test.
As a result, the wear depth of the slipper surface of test material Q was
3μ, and the wear depth of the slipper surface of test material R was 50μ. Practical test conditions: Engine rotation 1000 rpm Oil temperature 65°C Time 200 hours Example 10 Using the apparatus shown in Figure 1, work 1 for a stator consisting of a cast iron FCD55 Okoshi wear test piece was remelted as follows. That is, plasma arc current 80A, plasma arc Ar gas amount 0.8/
min, plasma torch scanning speed 0.3 m/min,
Remelt the sliding surface while drawing a trajectory, and add 5μ to 40μ FeS powder to the remelt layer at 1.5g/1.5g in Ar gas.
It was supplied in an amount containing min. The depth of the molten layer was 1.2 m/m. On this occasion,
One part of the added amount of FeS reacts with Fe, which is the main component of the alloy base material, and one part of Mn to generate (FeMn)S, and the iron sulfide as a whole is a mixture of FeS and (FeMn)S. A remelt hardened layer containing dispersed particles of the substance was formed. The size of the dispersed particles is 1~9μ
It was hot. Also, the volume ratio of FeS and (FeMn)S is 15
It was %. The sliding surface of the thus obtained treated product was polished to obtain a test piece S. For one-way comparison,
Test piece T was obtained by simply remelting the workpiece 1 made of the same material under the same conditions as above without adding iron sulfide. These were subjected to a wear test in the same manner as in Example 1 above. The test results were as follows.

[Table] Example 11 Using the apparatus shown in the first figure, a wear test piece made of S50C was used as work 1 for a stator, and this was remelted as follows. That is, plasma arc current
80A, plasma arc Ar gas flow rate 1/min, torch meandering scanning speed 0.3m/min, remelt the sliding surface while meandering, and add 10μ to 40μ MoS to the molten layer at a depth of 1.4m/m. 0.15 in Ar gas
It was fed at a feed rate containing g/min. As a result, a hardened layer in which MoS and FeMn, which is the alloy base material, react and FeS and (FeMn)S are generated and dispersed in the molten layer is obtained by subsequent cooling. The size of these produced particles was about 1 to 7 microns, and their volume ratio was about 0.8%. The treated surface was polished to obtain a test piece U. For comparison, Work 1 made of the same material was simply remelt hardened in the same manner as described above without adding such additives, and this was designated as Test Piece V. These test pieces were subjected to wear resistance tests in the same manner as described above, and the following results were obtained.

[Table] Example 12 Using the apparatus shown in Figure 1, a cam lift portion of an FC30 camshaft to be incorporated into an automobile engine was remelted as work 1 as follows. That is, plasma arc current 60A, arc Ar gas amount 0.5/min, plasma torch scanning speed 1
m/min, the surface of the cam lift part was melted while drawing a trajectory, and WS ₂ powder of 2 to 10 microns was supplied to the melted part at a supply rate of 0.6 g/min in gas. The depth of the molten layer was 1.8 m/m. As a result of its addition, a hardened layer of a molten layer in which FeS and (FeMn)S, which were generated by the reaction between WS ₂ and Fe and Mn, which are the constituent elements of the base material, were mixed and dispersed was obtained. The size of the dispersed particles was about 1 to 10 microns, and the volume ratio was 28%. The hardness of the hardened layer was HRC53. This camshaft was cam-polished to give a test material W. For comparison, the same camshaft was simply remelted and used as test material X. The hardness of the hardened layer is
It was HRC51. These test materials were tested at an engine speed of 1000 rpm and an oil temperature of 65.
It was subjected to a practical test under the test conditions of ℃ and test time of 200 hours. As a result, the amount of wear of test material U was 30μ, and the amount of wear of test material V was 120μ. Example 13 Using the apparatus shown in Figure 1, the slipper surface of the SCM420 valve rocker arm to be incorporated into an automobile engine was treated as work 1 by remelting as follows. That is, plasma arc current 45A,
The plasma Ar gas flow rate was 0.5/min, the plasma torch speed was 0.8 m/min, the slipper surface was scanned and melted, and the FeS was transported to the melted part using Ar gas.
It was supplied at a feed rate of g/min. part of the supply
FeS was produced in opposition to Mn, which is a constituent element of the alloy base material, and a molten hardened layer containing (FeMn)S mixed and dispersed together with FeS was obtained by cooling. The size of FeS and (FeMn)S was approximately 1 to 8 μm, and their volume ratio was approximately 3.2%. Next, in order to improve the strength of the slipper surface of the workpiece 1 treated in this way, carburizing and quenching is performed to form a carburized layer of approximately 1.2 mm on the hardened layer, and the sulfide is substantially contained in the carburized hardened layer. A wear-resistant tissue layer with a mixture of This surface was polished to obtain a test material W. For comparison, the same work 1
Test material For these test materials, engine rotation
Practical tests were conducted under the conditions of 1000 rpm, oil temperature of 65°C, and test time of 200 hours. As a result, test material W had a wear depth of 10μ, and test material X had a wear depth of 50μ. As is clear from Examples 1 to 13 above, Cr,
By dispersing and containing Mo, TiB, Al ₂ O ₃ , FeS, and other various sulfides in the remelt treatment layer of the workpiece, its wear resistance is significantly improved compared to those without such treatment. be able to. In particular, Cr sulfide has higher stability at high temperatures than other sulfides, and even at high temperatures of 1000°C or higher, it is more stable than other Cr sulfides.
Unlike sulfide powder, it does not decompose and provides an extremely stable frictional sliding surface, and also has the advantage of being effective as a lubricant. The particles to be added generally have a particle size of 200 μm or less, and preferably 100 μm or less.
When this is added to the molten layer on the surface of the workpiece, it becomes liquid droplets and is scanned by the plasma arc in this state, causing a fluid stirring phenomenon in the molten material.
The liquid phase particles are thereby finely divided, and as a result of being cooled and solidified in this state, a surface treatment layer in which the finely divided solid phase particles are dispersed in the hardened layer is obtained. For example, in the case of a cured product, the diameter of the dispersed particles is about 1 to
A range of 20μ is preferable, since it reduces the internal stress concentration rate, resulting in excellent pitting resistance, galling resistance, etc., and the lubricating effect of sulfide on the worn surface tends to act uniformly on the sliding surface. Further, by repeating the friction, the particles are stretched and a sulfide coating of tens to hundreds of angstroms is easily formed on the surface, which is preferable. Further, according to the present invention, the remelt time is generally only about 1 second or less, which is advantageous because there is almost no loss due to thermal decomposition of sulfides, for example. FIG. 7 shows the results of investigating the relationship between the volume percent of Cr sulfide and the amount of wear of the treated product for a camshaft made of FC30 automobile engine. As is clear from this, the effect of wear resistance is exhibited at approximately 0.2% or more, and the effect is remarkable even when a small amount is added. However, 12%
If the content exceeds a certain level, the toughness tends to decrease, and from the viewpoint that the effect is not improved much and it becomes economically expensive, it is advantageous to limit the content to about 12%. Figure 8 shows the results of investigating the relationship between the volume percent of iron sulfide powder (FeS+(FeMn)S) and the amount of wear of the treated product for a camshaft made of FC30 automobile engine. In this case, it is effective at 0.5% or more.
As the amount increases, the improvement in effectiveness decreases, and from an economical point of view, it is advantageous to limit the amount to about 20%. In this way, according to the present invention, the additive mixed into the molten zone by the plasma arc is forcibly mixed into the molten zone by breaking through the shielding gas flow of the plasma arc and being mixed into the molten zone along with the plasma arc. Since the alloy or compound containing the additive is formed in the molten zone, the additive is activated by partially melting in the jet stream of the plasma arc, and in this activated state, it is further absorbed into the base molten metal. As the alloy or compound is forcibly mixed into the base metal, it melts and stirs into the deep layer of the molten zone, increasing the alloying properties with the base metal, and the alloy or compound reaches the deep layer of the base metal, improving the base metal itself and improving its wear resistance and other properties. For example, when applied to the sliding surfaces of engine valve cams, it is possible to obtain excellent wear resistance.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of an example of an apparatus for carrying out the method of the present invention, FIGS. 2 to 6 are diagrams explaining the principle of each step of the method of the present invention, and FIGS. 7 and 8 are It is a curve diagram showing the relationship between volume % of sulfide and amount of wear. DESCRIPTION OF SYMBOLS 1... Workpiece, 2... Plasma torch, 10... Plasma arc, 11... Melting part, 12... Additive.

Claims (1)

[Scope of Claims] 1. Plasma arc generates a molten part on the surface of a workpiece made of cast iron, aluminum alloy, or other metal material, and the molten part is made of a metal material or other material different from the metal material of the workpiece. In the method of forming a remelt treatment layer by mixing additives and solidifying them by cooling, the additives are forced into the molten zone by breaking through the shielding gas flow of the plasma arc and accompanying the plasma arc. 1. A method for surface treatment of a workpiece, characterized in that an alloy or a compound containing the additive is formed in the molten zone. 2 The additives include Ni, Cr, Mo and other metals or their alloys, WC, SiC, MO ₂ C, Cr ₃ C ₂ , B ₄ C and other carbides, BN, TiB and other borides, MoS ₂ ,
The method for surface treating a workpiece according to claim 1, comprising at least one powder selected from WS ₂ , FeS and other sulfides, Al ₂ O ₃ , SiO ₂ and other oxides, and the like.