Mounting suction nozzle

Abstract

To provide a suction nozzle for mounting which has excellent mechanical strength such as bending strength and fracture toughness inherent in zirconia and is particularly suitable for mounting minute components.SOLUTION: In a suction nozzle for mounting with a brim made of partially stabilized zirconia and, if necessary, a conductive material, which has a tip suction surface that suctions and holds an object to be suctioned, and a rear end shaft that is fitted to a cylindrical flange at the rear stage, the outer peripheral surface of the suction nozzle for mounting other than the suction surface at the tip is a non-polished surface, and a flat portion with two molding marks extending in the axial direction is provided at an opposing position of the cross section of the rear end shaft portion.SELECTED DRAWING: Figure 1

Description

Detailed Description of the Invention [Technical field]

[0001] The present invention relates to a mounting suction nozzle made of partially stabilized zirconia that is suitably used in electronic component placement machines for mounting electronic chip components such as capacitor chips and resistor chips onto circuit boards. [Background technology]

[0002] In recent years, in the field of mounting circuit boards, electronic component placement machines capable of mounting minute chip components at high speed and high precision have been developed in line with the trend toward higher integration and higher precision of circuit boards. In this electronic component placement machine, a nozzle for suctioning and holding chip components is attached to the tip of a vacuum suction head that sucks in outside air, and the head moves back and forth between a feeder section and a circuit board. At this time, the chip components vacuum-sucked by the nozzle are mounted on the circuit board after the suction state of the chip components and the component mounting position are determined by image analysis while the head moves between the feeder section and the circuit board. This image analysis is performed by irradiating light from the front of the nozzle in the direction of the chip components and the suction surface, and analyzing the shape and electrode positions of the chip components from the difference in the amount of reflected light.

[0003] FIG. 4 is a schematic diagram showing an example of a process for mounting chip components onto a circuit board using this electronic component mounting machine.

[0004] An electronic component mounting machine 10 shown in Fig. 4 is composed of a mounting suction nozzle 1 for suctioning and holding a component mounted at the tip of its head, a tray 12 in a feeder section on which chip components 11 are arranged, a light 13 for irradiating light toward the chip components 11 sucked and held by the mounting suction nozzle 1, a CCD camera 14 for receiving light reflected from the chip components 11, and an image analyzer 15 for image processing of the reflected light received by the CCD camera 14. The mounting suction nozzle 1 has a suction surface 2 at its tip for sucking and holding an electronic component by vacuum suction as shown in Fig. 2, and has a through hole 4 in the nozzle axis portion that communicates from the rear end to the suction surface, and outside air is sucked from the tip of the through hole 4 in the direction of the rear end to suck and hold the chip components 11 on the suction surface 2.

[0005] In this electronic component mounting machine 10, when the mounting suction nozzle 1 moves to the tray 12 and picks up the chip component 11 arranged on the tray 12, the light 13 shines light onto the chip component 11 picked up by the nozzle 1, and the light reflected when this light hits the body of the chip component 11 or the like is received by the CCD camera 14. Based on the image received by the CCD camera 14, the misalignment and position of the chip component 11 are measured by the image analyzer 15, and based on this data, the nozzle 1 which has picked up the chip component 11 is moved to a predetermined position on the circuit board (not shown) and the chip component 11 is mounted on the circuit board.

[0006] Incidentally, in recent years, as mentioned above, chip components have become increasingly miniaturized in line with the increasing integration and precision of circuit boards. However, this miniaturization of chip components not only requires that the nozzles that attract and hold them be made smaller, their materials be strengthened, and their dimensional precision be increased, but also creates new problems due to the static electricity in the nozzle, such as electrostatic damage to chip components during mounting, and chip components that are attracted and held by the nozzle do not fall off even when the attraction is released, but can be taken away. As a countermeasure, there is an active movement to make the nozzle semiconductive to remove static electricity, and to change the material to ceramics, especially partially stabilized zirconia, which has excellent bending strength and fracture toughness, from the viewpoint of strengthening the nozzle material, improving its precision, and further heat resistance. In addition, when the nozzle is installed in an electronic component placement machine, the nozzle rear end shaft is fitted into a metallic cylindrical flange 8 as shown in FIG. 2 in order to mitigate the impact on the components, and the nozzle is assembled. In order to improve the assembly precision, the nozzle side surfaces other than the suction surface and the nozzle rear end shaft that comes into contact with the flange 8 are polished (hereinafter, in this invention, secondary processing such as polishing and grinding will be referred to simply as "polishing") before assembly.

[0007] However, partially stabilized zirconia has a problem in that the crystal phase undergoes a phase transformation due to excessive polishing of the outer peripheral surface of the nozzle after molding and sintering, or due to the thermal history in the atmosphere in which it is used, resulting in a significant decrease in bending strength and fracture toughness. For this reason, for example, Patent Document 1 reports a method for specifying the particle size of the zirconia used, but this method is unable to prevent the decrease in strength and fracture toughness due to the phase transformation specific to zirconia, and this has been a major obstacle to miniaturizing the nozzle. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] WO2009-91061 publication Summary of the Invention [Problem to be solved by the invention]

[0009] In view of the above circumstances, an object of the present invention is to provide a nozzle that has excellent mechanical strength, such as bending strength and fracture toughness, inherent to zirconia, and is particularly suitable for mounting micro-components. [Means for solving the problem]

[0010] In order to solve the above problems, the inventors have thoroughly investigated the material properties of zirconia, in particular the effect on mechanical strength of the thermal history during nozzle polishing, and have earnestly studied the best way to avoid polishing. As a result, based on the finding that polishing the surface of the nozzle significantly reduces the proportion of tetragonal zirconia in its crystal phase, and significantly impairs the high mechanical strength that is characteristic of zirconia, they have found that the most efficient and practical method for avoiding polishing is to provide a structure in which a flat portion bearing molding marks is left on the rear end shaft portion of the nozzle, and have completed the present invention.

[0011] That is, a first aspect of the present invention is a mounting suction nozzle with a flange made of partially stabilized zirconia and equipped with a tip suction surface for suctioning and holding an object to be suctioned, and a rear end shaft portion to be fitted into a cylindrical flange at a rear stage, characterized in that the outer peripheral surface of the mounting suction nozzle other than the tip suction surface is a non-polished surface, and flat portions with two axially extending molding marks are provided at opposing positions on a cross section of the rear end shaft portion. A second aspect of the present invention is a mounting suction nozzle in which, in the nozzle rear end shaft portion of the first aspect, a ratio A / B of a shaft diameter A connecting the flat portions to a shaft diameter B of the other than the flat portions is 0.85 to 0.98. A third aspect of the present invention is a mounting suction nozzle in which 90% or more of the zirconia crystal phase in the nozzle outer peripheral surface other than the tip suction surface is composed of tetragonal crystals. A fourth aspect of the present invention is a nozzle in the first aspect of the present invention, wherein the nozzle includes a conductivity imparting material, and the resistance between the tip suction surface and the rear end shaft portion is 10 2 ~10 10 A fifth aspect of the present invention is a mounting suction nozzle according to the first aspect of the present invention, wherein the conductivity imparting material is at least one selected from titanium oxide, iron oxide, chromium oxide, cobalt oxide, nickel oxide, silicon carbide, and silicon nitride. Effect of the Invention

[0012] According to the present invention, in a flanged mounting suction nozzle made of partially stabilized zirconia and equipped with an suction surface at its tip for suctioning and holding a chip component, by providing a flat portion carrying molding marks on the rear end shaft of the nozzle, the outer periphery other than the suction surface can be used as a non-polished surface, which not only suppresses the decrease in strength such as bending strength and fracture toughness caused by changes in the zirconia crystal phase due to polishing, but also significantly improves the bonding strength with the downstream cylindrical flange, thereby dramatically increasing the practical durability of the nozzle, which in turn not only makes it possible to miniaturize the nozzle but also contributes to improving the mounting accuracy of electronic components.

[0013] Furthermore, if the mounting suction nozzle of the present invention further contains a conductivity imparting material in addition to the partially stabilized zirconia, it can also solve new problems caused by static electricity in the nozzle, such as electrostatic damage to chip components during mounting, and chip components that are suctioned and held by the nozzle do not fall away even when the suction is released, but are instead carried away. [Brief description of the drawings]

[0014] [Figure 1] FIG. 1 is a perspective view showing an example of a mounting suction nozzle of the present invention. [Diagram 2] FIG. 2 is a side cross-sectional view showing a typical example of assembly of the mounting suction nozzle of the present invention and a cylindrical flange at the rear stage. [Diagram 3] FIG. 3(a) is an example of a rear view of the mounting suction nozzle of the present invention as seen from the rear-end shaft side, and FIG. 3(b) is a partially enlarged cross-sectional view showing an example of a flat portion provided on the rear-end shaft indicated by the dashed circle in FIG. [Figure 4] FIG. 4 is a schematic diagram showing an example of the configuration of an electronic component mounting apparatus that mounts chip components on a circuit board using an electronic component mounter equipped with a mounting suction nozzle of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] The present invention will be described in detail below.

[0016] FIG. 1 is a perspective view showing an example of a mounting suction nozzle of the present invention, and FIG. 2 is a cross-sectional view showing an example of the configuration when this mounting suction nozzle is attached to a cylindrical flange in the subsequent stage.

[0017] The mounting suction nozzle 1 shown in Figures 1 and 2 comprises a tip suction surface 2 that suctions and holds an object to be suctioned, and a rear end shaft portion 3 that is fitted into a rear cylindrical flange 8, and is an mounting suction nozzle with a flange 5 having a through hole 4 from the suction surface 2 toward the rear end shaft portion 3, and the outer peripheral surface of the mounting suction nozzle 1 other than the tip suction surface 2 is a non-polished surface, and a flat portion 6 is provided at opposing positions on the cross section of the rear end shaft portion on which two axially extending molding marks 7 (see Figure 3(b) described below) remain.

[0018] The mounting suction nozzle 1 of the present invention is a sintered compact mainly made of partially stabilized zirconia, which is produced by adding binders, molding aids, etc. to a mixture of partially stabilized zirconia and, if necessary, a conductivity imparting material, kneading the mixture, and drying it using a known method such as a spray dryer to produce a powder or granular raw material. This is then injection molded into a nozzle shape with a brim, and further undergoing desolvation and sintering processes.

[0019] In the present invention, the partial stabilizer for zirconia is preferably one of yttrium oxide, magnesium oxide, calcium oxide, cerium oxide, etc., and among them, yttrium oxide is preferable. The amount of yttrium oxide added is 1 to 5 mol%, preferably 2 to 4 mol%, and if it is less than 1 mol%, the amount of monoclinic zirconia increases, causing many cracks inside the sintered body and reducing the mechanical strength, while if the amount of yttrium oxide added exceeds 5 mol%, a lot of cubic zirconia is generated in the sintered body, and in this case too, high mechanical strength cannot be expected. Outside the above range of 1 to 5 mol%, there are inconveniences such as less generation of tetragonal zirconia that produces the stress-induced phase transformation function unique to zirconia.

[0020] Furthermore, the average crystal grain size of the partially stabilized zirconia used in the present invention is preferably 0.2 to 3.0 μm. If the average crystal grain size is less than 0.2 μm, the stress-induced phase transformation function is not fully exhibited, and therefore excellent mechanical strength such as bending strength and fracture toughness cannot be obtained. On the other hand, if the average crystal grain size is more than 3.0 μm, deterioration over time at relatively low temperatures of about 100 to 300° C. is likely to progress, and wear resistance, impact resistance, etc. will decrease.

[0021] On the other hand, the conductivity imparting material used as necessary in the present invention is not particularly limited as long as it is a material that can impart conductivity, but among them, at least one selected from oxygen-deficient titanium oxide, iron oxide, chromium oxide, cobalt oxide, nickel oxide, manganese oxide, silicon carbide, silicon nitride, and other metal oxides, carbides, and nitrides is preferred in that it can impart conductivity with a relatively small amount of addition. The amount of these conductivity imparting materials to be added is such that the electrical resistance between the tip and rear end of the nozzle, which is necessary to avoid problems caused by static electricity or electrification of the nozzle, such as electrostatic breakdown or takeaway of components during mounting of electronic components, and further blow-off and contamination of components, is 10 2 ~10 10 The amount of the conductivity enhancer may be appropriately determined so as to achieve Ω depending on the type of conductivity enhancer. For example, in the case of metal oxides such as iron oxide and chromium oxide, the amount added is preferably 20 to 40% by weight relative to the partially stabilized zirconia, and in the case of oxygen-deficient titanium oxide, the amount added is preferably 10 to 20% by weight relative to the partially stabilized zirconia.

[0022] Here, oxygen-deficient titanium oxide is a product of partially deficiency of oxygen in titanium dioxide by reducing and firing a molded body of partially stabilized zirconia with titanium dioxide or the like in an atmosphere of argon or nitrogen under conditions of 1300 to 1500°C, and is preferably represented by the chemical formula TiOx (1.50≦X≦1.95) and having an average crystal grain size of about 0.03 to 0.30 μm. That is, titanium dioxide is white and an insulator at room temperature, but when reduced and fired at high temperatures, oxygen deficiency occurs, the color changes from gray to blue-black to true black, and the electrical conductivity increases. When the X value in the chemical formula TiOx of the oxygen-deficient titanium oxide is less than 1.50, the crystal is easily changed to a NaCl type structure, causing volumetric shrinkage and decreasing strength, while when the X value exceeds 1.95, the blackness and electrical conductivity are insufficient and the desired mounting nozzle cannot be obtained.

[0023] In the present invention, the amount of oxygen in oxygen-deficient titanium oxide, i.e., the X value of TiOx, can be calculated by subjecting the mounting nozzle after reduction firing to a thermal analysis (TG-DTA) at room temperature to 1000°C at a heating rate of 20°C / min in air, since oxygen-deficient titanium oxide is usually oxidized to titanium dioxide at a temperature of 500 to 600°C in air and changes from black to white, and determining the X value from the weight increase during that period as the increase in oxygen due to oxidation.

[0024] The mounting suction nozzle 1 of the present invention is made of the above-mentioned partially stabilized zirconia, and the outer peripheral surface of the nozzle other than the tip suction surface 2 is a non-polished surface, and a flat portion 6 bearing two axially extending molding marks 7 is provided at opposing positions on the cross section of the rear end shaft of the nozzle.

[0025] In other words, with conventional mounting suction nozzles, not only the suction surface that picks up the electronic component, but also the other outer surfaces must reliably pick up and hold the component and transport it accurately to a predetermined position on the circuit board and attach it to that position. Therefore, polishing was essential to achieve high dimensional accuracy and surface precision in order to improve the accuracy of assembly with other components such as the downstream flange and sleeve parts to which the nozzle is fixed.

[0026] However, as described above, zirconia has a unique stress-induced phase transformation function in which mechanical strengths such as bending strength and fracture toughness are greatly affected by the state of its crystal phase, i.e., the proportion of tetragonal zirconia in the total zirconia crystal phase determined by X-ray diffraction. Therefore, when a nozzle after sintering is polished, part of the crystal phase is transformed from tetragonal to monoclinic due to the thermal history such as frictional heat during polishing, and the stress-induced phase transformation function does not work, making it impossible to obtain high mechanical strength, which is a major obstacle to miniaturizing the nozzle.

[0027] From the above viewpoint, the mounting suction nozzle 1 of the present invention has an outer peripheral surface of the nozzle other than the tip suction surface 2 as a non-polished surface, and specifically, it is preferable that 90% or more of the zirconia crystal phase on the outer peripheral surface of the nozzle is tetragonal; if the proportion of tetragonal is less than 90%, the high mechanical strength achieved by the stress-induced phase transformation cannot be obtained, making it difficult to miniaturize the nozzle.

[0028] Here, the stress-induced phase transformation function of partially stabilized zirconia refers to the property of tetragonal zirconia undergoing a stress-induced phase transformation to monoclinic zirconia, of the three crystalline states of zirconia sintered bodies: cubic, tetragonal, and monoclinic. During this phase transformation from tetragonal to monoclinic, volume expansion occurs, generating tiny microcracks around the zirconia, preventing the progression of the external stress, thereby increasing the bending strength and fracture toughness of the zirconia.

[0029] In the present invention, the amount of tetragonal zirconia on the outer peripheral surface other than the adsorption surface was calculated according to the method described in JP 2010-254493 A, in which the contents (volume %) of monoclinic zirconia (measured at a diffraction angle of 27 to 34 degrees) and cubic zirconia (measured at a diffraction angle of 70 to 77 degrees) were determined by X-ray diffraction, and then the tetragonal zirconia content was calculated by the following formula: Formula 1 Tetragonal zirconia content (volume %) = 100 - monoclinic zirconia content - cubic zirconia content

[0030] Furthermore, in the present invention, in order to increase the hardness of the mounting suction nozzle or to make the surface roughness uniform, within the scope of not impairing the performance of the nozzle, it is possible to carry out a well-known method such as blasting, silicate coating, or HIP treatment, and it is also possible to further add other ceramic materials such as alumina or molybdenum.

[0031] In order to make the outer peripheral surface other than the tip suction surface 2 of the mounting suction nozzle 1 of the present invention a non-polished surface, flat portions 6 with two axially extending molding marks 7 are provided at opposing positions on the cross section of the rear end shaft portion 3 that is fitted into the rear cylindrical flange 8 as shown in Figures 2 and 3.

[0032] That is, mounting suction nozzles are usually manufactured by injection molding machines in consideration of mass production, but to injection mold a flanged nozzle as in the present invention, a molding die is used in which a die (hereinafter referred to as "die 1") for molding the part from the tip suction surface to the rear end of the flange and a die (hereinafter referred to as "die 2") for molding the part from the rear end of the flange to the rear end of the shaft are arranged in the nozzle axial direction, the nozzle raw material is injection molded into the communicating dies 1 and 2, the molded body is cooled, and each die is opened to remove the molded body. In this case, a one-piece die can be used for die 1 because the molded body is tapered toward the tip suction surface, but a pair of split dies that split in two directions must be used for die 2 for molding the part from the rear end of the flange to the rear end of the shaft in order to smoothly remove the molded body. However, with this pair of split molds, the pressure applied during injection molding leaves molding marks such as burrs and chips at the joints of the molds, and so when assembling the mold with the subsequent cylindrical flange, the molding marks had to be polished away.

[0033] In order to make it unnecessary to remove such molding marks, the mounting suction nozzle 1 of the present invention is provided with flat portions 6 at opposing positions on the cross section of the nozzle rear end shaft portion, which leave two axially extending molding marks 7. These two axially extending flat portions 6 are located approximately in the center of the molding mark 7 remaining at the seam of the split mold, as shown in Fig. 3. By providing such flat portions 6, a clearance can be created between the inner circumference of the flange and the outer circumference of the rear end shaft portion, and even a relatively large molding mark can be contained within the clearance, making it possible to use the nozzle in an unpolished state.

[0034] As described above, by providing the flat portion 6 on the rear end shaft portion of the mounting suction nozzle of the present invention, polishing of the outer circumferential surface of the nozzle, including the removal of molding marks, which has been previously considered essential, is not necessary. This is particularly effective in shortening the nozzle processing process and reducing costs. In addition, the decrease in strength of the partially stabilized zirconia caused by the polishing process described above is suppressed, and when assembling with the cylindrical flange in the subsequent stage, the clearance between the inner periphery of the flange and the rear end shaft portion is increased, making the fixation with adhesive stronger and suppressing rotation of the nozzle. These are some of the excellent features that ultimately contribute greatly to the miniaturization of the nozzle.

[0035] In the nozzle of the present invention, the size of the flat portion 6 is preferably set in a range such that the ratio A / B of the shaft diameter A connecting the flat portions to the shaft diameter B of the portions other than the flat portions shown in Fig. 3(A) is 0.85 to 0.98, preferably 0.90 to 0.95. The reason is that if the shaft diameter ratio is less than 0.85, the strength of the rear end shaft portion is weakened, causing durability problems, while if the shaft diameter ratio is greater than 0.98, the molding marks cannot be contained within the clearance, and grinding is required. In the present invention, the smaller the height of the molding marks is, the larger the shaft diameter ratio can be, so it goes without saying that the pressure during injection molding, the molding temperature, etc. must be optimized.

[0036] In the present invention, the flat portion 6 does not necessarily have to be a flat surface, and may have some curved or uneven surfaces as long as the molded product can be removed from the split mold. EXAMPLES

[0037] In order to facilitate understanding of the present invention, experimental examples will be described below in which the change in mechanical strength of a partially stabilized zirconia molded body depending on whether or not it is polished, but the present invention is not limited to these examples.

[0038] (Experimental Examples 1-3, Control Examples 1-3) A compound raw material was prepared by adding 15% by weight of titanium dioxide having an average particle size of 0.07 μm to partially stabilized zirconia having an average crystal grain size of 1.0 μm containing 3 mol% of yttrium oxide, adding acrylic or ethylene vinyl acetate binders and waxes, and kneading and drying the mixture. The compound raw material was then injection molded under the conditions of a mold temperature of 40°C and an extrusion temperature of 150°C to obtain a molded product. The molded product was desolvated under the conditions of 450-900°C in air, and then fired at a temperature of 1100°C-1600°C for 1 hour in an inert gas mainly composed of nitrogen to prepare a test piece with a cross-sectional dimension of 3 mm x 4 mm and a length of 40 mm. The obtained test pieces were either left unpolished or polished to obtain samples with different contents of tetragonal zirconia in the surface zirconia crystal phase.

[0039] The crystal phase, bending strength, and electrical resistance of the obtained samples were evaluated by X-ray diffraction method, and the results are summarized in Table 1. The surface crystal phase of the obtained samples was composed only of monoclinic zirconia and tetragonal zirconia, and the presence of cubic zirconia was not observed.

[0040] In the experimental examples and the control examples, the bending strength and the electrical resistance were evaluated by the following methods.

[0041] The bending strength of each sample was measured by the four-point bending strength method according to JIS R1601 (2008).

[0042] The electrical resistance was measured by contacting electrodes with the adsorption surface at the tip and the rear end of the nozzle shown in Figure 1, which was produced with the same composition and manufacturing conditions as each sample, and connecting a surface resistance meter between these electrodes to apply a voltage, thereby measuring the resistance (Ω) between the tip and rear end of the nozzle.

[0043] [Table 1]

[0045] From the results in Table 1, the surface crystal phase of the polished sample has a lower proportion of tetragonal zirconia, resulting in low bending strength and poor electrical conductivity. On the other hand, the sample that was not polished had a high tetragonal zirconia content, and was confirmed to have excellent bending strength and electrical conductivity, making it suitable for use as a component suction nozzle for electronic component placement machines. Note that, in Table 1, the electrical conductivity was deteriorated by polishing, but this is presumably due to the oxidation of part of the oxygen-deficient titanium oxide used as the electrical conductivity imparting material by polishing in the air. [Industrial Applicability]

[0046] The mounting suction nozzle of the present invention has many advantages, including excellent mechanical strength such as bending strength and fracture toughness, and, when a conductivity imparting material is added, extremely low occurrence of problems such as electrostatic breakdown and blowing away of components, even as chip components become smaller and mounting speeds increase, making it extremely suitable for use in the mounting of electronic components, particularly in the field of mounting very small components. [Explanation of symbols]

[0047] 1; Mounting suction nozzle 2; Tip suction surface 3; Rear end shaft part 4;Through hole 5; Tsuba 6; flat area 7; Molding marks 8; Cylindrical flange 10. Electronic component mounting device 11. Chip components 12;tray 13;Light 14. CCD camera 15. Image analysis device

Claims

1. This mounting suction nozzle is made of partially stabilized zirconia and has a tip suction surface for suctioning and holding an object to be suctioned, and a rear end shaft portion for fitting into a cylindrical flange at a rear stage. The mounting suction nozzle is characterized in that the outer peripheral surface other than the tip suction surface of the mounting suction nozzle is a non-polished surface, and two flat portions with molding marks extending in the axial direction are provided at opposing positions on the cross section of the rear end shaft portion.

2. 2. The mounting suction nozzle according to claim 1, wherein the cross-sectional shape of the rear end shaft portion has a ratio A / B of a shaft diameter A connecting the flat portions to a shaft diameter B other than the flat portions of 0.85 to 0.

98.

3. 3. The mounting suction nozzle according to claim 1, wherein 90% or more of the zirconia crystal phase on the outer peripheral surface of the nozzle other than the tip suction surface is composed of tetragonal crystals.

4. The mounting suction nozzle includes a conductive material, and the resistance between the tip suction surface and the rear end shaft portion is 10 ２ ~10 １０ 4. The mounting suction nozzle according to claim 1, wherein said suction nozzle is Ω.

5. 5. The mounting suction nozzle according to claim 1, wherein the conductivity imparting material is at least one material selected from the group consisting of titanium oxide, iron oxide, chromium oxide, cobalt oxide, nickel oxide, silicon carbide, and silicon nitride.

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