碳含量对Cr25系高铬铸钢组织及性能的影响

研究了碳含量(0.13%,0.25%,0.32%,质量分数)对Cr25系高铬铸钢显微组织、高温抗氧化性能及高温耐磨性的影响。结果表明:不同碳含量铸钢的显微组织均由铁素体和(Cr·Fe)23C6型碳化物组成,随着碳含量增加,碳化物由不连续长杆状转变成连续网状,且由完全沿晶析出逐步转成沿晶和晶内析出;在1 200℃高温氧化初期,试验钢快速氧化,氧化40h后,因表面形成致密的铬氧化物保护层,氧化速率趋缓,进入稳定氧化阶段;随着碳含量增加,试验钢的高温抗氧化性降低,耐磨性增强,磨损机制由黏着磨损变为黏着及磨粒磨损共同作用机制。     

合金化提高碳化物高温化学稳定性的研究

对含不同合金元素Mo、W和B的高Cr-Ni铸铁在大气中进行了800℃及950℃的恒量氧化试验。结果表明,经Mo、W和B适量合金化后的碳化物在高温下的化学稳定性有不同程度的提高。从原子间结合力和合金热力学的角度讨论了合金元素对（Cr,Fe）7C3型碳化物高温化学稳定性的影响。     

DZ4合金渗铝-硅涂层1 100 ℃氧化时的元素扩散规律

以定向凝固镍基高温合金DZ4为基体,采用料浆法在合金表面制备铝-硅涂层;对该涂层试样进行1100℃抗高温氧化性能试验,并对氧化过程中各元素的分布进行了分析.结果表明:随氧化时间增加,涂层逐渐分为两层,外层为单一β-NiAl相,内层主要由β-NiAl相构成,层内分布着块状和颗粒状的碳化物;高温氧化过程中,硅元素不断向涂层内部扩散,并与基体合金中向外扩散的钼、钨元素结合形成富硅的M6C,并逐渐形成M6C隔层,阻碍镍与铝的互扩散,提高了涂层在高温下的抗氧化能力.     

镍包SiC_p增强Ni35合金激光熔覆层的显微组织及摩擦磨损性能

采用激光熔覆工艺在H13模具钢基体表面制备镍包SiC_p增强Ni35合金熔覆层,研究了熔覆层的显微组织以及在25,600℃下的摩擦磨损性能。结果表明:熔覆层由γ-Ni(Fe)+M_3(B,Si)共晶相、M_(23)C_6型碳化物、M_7C_3型碳化物、Ni_(31)Si_(12)镍硅化物和石墨组成;在不同温度下摩擦磨损后,熔覆层表面的显微硬度均高于基体的,磨损体积小于基体的;25℃下熔覆层的耐磨性能较基体的明显提高,且提高效果高于600℃下的;25℃下熔覆层的磨损机制主要为微磨粒磨损和黏着磨损,600℃下的则主要为磨粒磨损、黏着磨损以及轻微的氧化磨损。     

镍、铬、铝对铁基高温合金组织和性能的影响

镍、铬、铝在铁基高温合金中应该适量加入,γ'相、σ相、碳化物等在试验合金凝固和时效过程中析出的形态和数量对基体组织的各方面性能都有较大的影响.高温下,试验合金的抗氧化能力取决于其表面形成的氧化膜成分.本文将从试验合金的高温拉伸强度和高温氧化增重速率两个方面,配以SEM二次电子像、能谱分析以及X-射线衍射分析,综合研究镍、铬、铝三元素对铁基高温合金组织和性能的影响规律.     

镍、铬、铝对铁基高温合金组织和性能的影响

镍、铬、铝在铁基高温合金中应该适量加入,γ相、σ相、碳化物等在试验合金凝固和时效过程中析出的形态和数量对基体组织的各方面性能都有较大的影响。高温下,试验合金的抗氧化能力取决于其表面形成的氧化膜成分。本文将从试验合金的高温拉伸强度和高温氧化增重速率两个方面,配以SEM二次电子像、能谱分析以及X-射线衍射分析,综合研究镍、铬、铝三元素对铁基高温合金组织和性能的影响规律。     

高铬耐磨铸造合金的组织及其磨损

本文介绍一种含碳量为2.0%,含铬量为30.0%的铸造耐热耐磨合金材料。由于合金含有较高的铬和碳,在凝固过程中,形成一种致密、坚硬耐磨性好的铬碳化物(Cr_7C_3)耐磨质点,它比铁碳化物(Fe_3C)的硬度和韧性要优越得多。采用光学显微镜,扫描电子显微镜及X光衍射研究了合金的显微组织、碳化物形态及分布。合金的组织是由γ-Fe固溶体、碳化物及少量α铁素体组成。经相组成分析和Quantimet-720图象分析仪,测定γ-Fe固溶体量为70%,碳化物量为20%,α铁素体量为10%。碳化物形态有共晶花样型和块状二种,牢牢地银嵌在γ-Fe固溶体内。因此合金既有良好的耐磨性、韧性、又有好的机械加工性能。在不同磨损条件下对比了合金的抗磨损特性,并采用扫描电镜分析了合金的磨损情况。该合金采用感应熔炼,精密铸造成型。合金耐磨性能好,有良好的高温性能,在实际生产中使用,收到显著的经济效果。     

含钨—石墨镍基合金的高温摩擦学性能

用粉末冶金方法制备了含钨—石墨以及其他增强相的镍基合金材料,评价了材料在室温至700℃条件下的摩擦磨损性能。结果表明,室温条件下,热压过程中生成的硬质碳化物、石墨的润滑作用,以及合金表面的摩擦细化作用,使材料表现出良好的摩擦磨损性能; 200℃和400℃条件下,合金表面石墨的氧化分解及成膜能力不足．导致摩擦学性能下降; 600℃和700℃时,高温氧化生成的氧化物及钨酸盐在摩擦面形成的固体润滑膜改善了润滑条件,摩擦因数降低,且较为稳定,磨损体积由于氧化而增大。     

激光熔覆Ni60和Co-Cr-W合金层的高温磨损特性研究

在4Cr14NiW2Mo耐热合金钢表面熔覆Ni60和Co-Cr-W合金粉末，获得具有良好冶金结合和组织致密的熔覆层。在不同温度条件下（室温、250℃和420℃），对Ni60和Co-Cr—W熔覆层及其基体材料进行了摩擦磨损试验。研究结果表明：Co-Cr-W熔覆层和基体材料的磨损机制为磨粒磨损、剥层和氧化磨损的共同作用，其摩擦因数随温度的升高而降低；对于Ni60熔覆层，其摩擦因数几乎不受温度的影响，其磨损机制表现为磨粒磨损。在高温条件下，Ni60熔覆层比Co-Cr-W合金熔覆层具有更优良的高温摩擦磨损性能。     

镍基合金Inconel718可切削加工性的试验研究

Inconel718是一种高强度耐热镍基合金,具有优良的高温强度、高温硬度和耐蚀性,在高温条件下能长期工作,已被广泛地应用于宇航工业、航空工业的涡轮发动机和相关零件的制造。分析Inconel718的机械性能、微观组织结构及其对切削加工性能的影响并进行了相关的试验验证,在试验数据的基础上,研究Inconel718中含碳量对切削过程中刀具磨损的影响。试验结果表明,Inconel718中含碳量在刀具后刀面磨损中起着非常重要的作用,Inconel718合金中含碳量越高,合金中所含的细微硬质夹杂物也越多,在切削过程中使刀具产生严重的后刀面磨粒磨损,从而降低材料的切削加工性。     

沉积温度对脉冲真空弧源沉积类金刚石薄膜性能的影响

利用脉冲真空弧源沉积技术在Cr17Ni14Cu4不锈钢和Si(100)基体上制备了类金刚石(DLC)薄膜,研究了基体沉积温度对DLC薄膜的性能和结构的影响。研究表明,随着沉积温度由100 ℃提高到400 ℃,DLC薄膜中sp3 键质量分数减少,sp2键质量分数增多,薄膜复合硬度逐渐降低。当DLC薄膜沉积温度达到400 ℃时,薄膜中C原子主要以sp2键形式存在,与沉积温度为100 ℃时制备的DLC薄膜相比,薄膜复合硬度降低50%。DLC薄膜具有优异的耐磨性,摩擦因数低,随着沉积温度由100 ℃提高到400 ℃,Cr17Ni14Cu4不锈钢表面沉积的DLC薄膜耐磨性降低。沉积温度为100 ℃时,Cr17Ni14Cu4不锈钢表面沉积的DLC薄膜后,耐磨性大幅度提高。DLC薄膜与不锈钢基体结合牢固。     

Erosive wear of selected metals in coal washing environments

A slurry erosive wear apparatus developed by the authors has been used to test the erosive wear behaviour of selected metals in coal washing environments. The erosive wear test machine was employed to determine the effects of (1) carbon content in carbon steels, (2) chromium content in alloy steels, and (3) corrosion of aqueous solutions on the erosive wear behaviour of metals. The test results revealed that the carbon content in annealed carbon steels slightly affects the erosive wear resistance of metals, while the increase in chromium content of alloy steels apparently improves the erosive wear resistance of metals and, when a corrosion inhibitor is added to slurries, the erosive wear rates of metals reduces significantly. Two types of micro-mechanism were deduced from the observation of eroded surfaces by SEM: (1) local exfoliation, and (2) micro-cutting. The corrosion inhibitor can alter the micro-mechanism from local exfoliation to micro-cutting. The analyses show that the erosive wear of selected metals in slurries results from the synergistic effects of wear by solid particles plus fluid corrosion.     

Cr5系堆焊合金碳、铬过渡形式对高温磨损性能影响的研究

在轧辊堆焊复合制造中,为节约贵重碳化物及提高堆焊材料的性价比,在堆焊熔敷金属成分基本保持不变的条件下,利用埋弧堆焊研究药芯焊丝碳、铬不同加入方式对堆焊合金微观组织与性能的影响。通过磨损试样前后硬度、高温拉伸、常温韧性与高温磨损量的量化,结合磨损前后金相组织、扫描电镜等辅助手段分析微观组织、加入方式与耐磨性之间的关系;结果表明:堆焊金属600℃的高温耐磨性能与合金高温强度及硬度呈正比,并随合金韧性的增加耐磨性能提高;直接加石墨和铬粉的药芯焊丝堆焊熔敷金属的耐磨性能优于在焊丝中直接加碳化铬的堆焊熔敷金属。高温磨损是合金氧化、切削、疲劳开裂与剥离等多种因素作用的结果,理想的高温耐磨堆焊材料不仅与采用的堆焊合金系有关,还与堆焊金属的显微组织、抗氧化性能及高温强韧性等因素有关。同时得出改变合金的加入方式是不添加变质剂及外加激振法外,能够促使组织均匀及强化熔敷金属的另一种方式。     

Studies on high temperature wear and its mechanism of Al-Si/graphite composite under dry sliding conditions

Wear behaviours of aluminum silicon alloy and Al-Si/graphite composite were investigated at ambient and elevated temperatures. The trend showed a decrease in wear rate with increase in temperature. The reduction in wear rate was mainly attributed to the formation of glazing layer and oxide layer at higher temperature. This was invariably observed in alloy and composites. In addition, the presence of graphite in composite offered better wear resistance for all temperatures under consideration. The wear due to oxidation was predominant during high temperature sliding.     

TiAl基合金成分对其高温摩擦学性能的影响

指出TiAl基合金高温摩擦学性能主要由高温抗氧化性、高温强度及高温自润滑性能所决定;综述了TiAl基合金成分对其高温抗氧化性、高温强度以及高温自润滑性能的影响,最后探讨了TiAl基合金作为高温耐磨结构材料的设计方法。     

The unlubricated adhesive wear resistance of metastable austenitic stainless steels containing silicon

The unlubricated adhesive wear resistance of metastable austenitic stainless steels can be improved by silicon additions. At low surface temperatures (under the M_d temperature) metastability appears helpful in maintaining the alloy in a state of mild wear. Silicon was not found to promote alloy metastability but did tend to strengthen the alloy by solid solution hardening. At lower temperatures the silicon had little effect on the mild wear rates of metastable alloys but did act to lower the severe wear rates of stable alloys. At high surface temperatures (above the M_d temperature) the silicon additions (2–4%) were found very beneficial in promoting mild wear rates while metastability had little or no effect. Silicon additions were also found to be beneficial to the oxidation resistance and did not increase the running-in period for the alloys. Improving the oxidation resistance of these alloys is more effective in promoting mild wear than is increasing the hardness through metastability.     

Tribological properties of Ni-17.5Si-29.3Cr alloy at room and elevated temperatures

The tribological properties of Ni-17.5Si-29.3Cr alloy against Si₃N₄ were studied on a ball-on-disc tribotester between room temperature and 1000 °C. The effects of temperature on the tribological properties of the alloy were investigated. The worn surfaces of the alloy were examined using scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The results indicated that the tribological behavior of the alloy expressed some differences with increase in testing temperature. At low and moderate temperatures (below 800 °C), the alloy showed excellent wear and oxidation resistances, and the wear rate of the alloy remained in the magnitude of 10^?5 mm³/Nm; but at elevated temperature (800–1000 °C), the wear and oxidation resistances decreased, and the wear rate of the alloy increased up to 10^?4 mm³/Nm. The friction coefficient decreased from 0.58 to 0.46 with the rising of testing temperature from 20 to 600 °C, and then remained nearly constant. The wear mechanism of the alloy was mainly fracture and delamination at low and moderate temperatures, and transformed to adhesive and oxidation at elevated temperatures.     

耐高温磨损的合金钢导辊及高温耐磨性能研究

研究了一种具有奥氏体基体及碳化物硬质点的合金钢 ,并用于制造高速线材轧制生产线上的导辊 ,使用温度在 5 6 0℃下 ,合金钢导辊具有良好的耐磨性。分析了时效温度对奥氏体基体硬度及合金钢耐磨性的影响 ,研究表明提高奥氏体基体的硬度对改善合金钢高温耐磨性具有明显的作用。     

Effects of carbon content on the high temperature friction and wear of chromium carbonitride coatings

Chromium nitride-based coatings are often used in application at high temperature. They possess high wear and oxidation resistance; however, the friction coefficient is typically very high. Therefore, we doped CrN coatings by carbon with the aim to improve tribological properties at elevated temperature, particularly to lower the friction. CrCN coatings were prepared by cathode arc evaporation technology using constant N₂ flow and variable C₂H₂ flow. The coatings with a thickness of 3-4 μm were deposited on hardened steel substrates and high-temperature resistant alloy. The carbon content varied from 0 at.% (i.e. CrN) up to 31 at.%. The standard coating characterization included the nano-hardness, adhesion, chemical composition and structure (including hot X-ray diffraction). Wear testing was done using a high temperature tribometer (pin-on-disc); the maximum testing temperature was 700 °C. The coatings with carbon content 12-31 at.% showed almost identical tribological behaviour up to 700 °C.     

Influence of alumina dispersoid and test parameters on erosive wear behaviour of a cast zinc–aluminium alloy

Observations made pertaining to the erosive wear characteristics of a cast zinc-based alloy and its composite containing 10 wt.% (corresponding to 11.2 vol.%) alumina particles have been presented in this study. Matrix alloy has also been tested under identical test conditions in order to examine the role played by second phase alumina particles on the erosive wear resistance of the matrix alloy. Eroded surfaces and subsurface regions of the specimens were also characterized to understand the operating wear mechanisms.The composite exhibited higher erosive wear resistance (inverse of erosive wear rate) than the unreinforced matrix alloy in general. Further, the wear rate increased with increasing impingement velocity as also evident from higher surface damage. Increasing angle of impingement at lower impinging velocity led to reduced erosive wear rate. On the contrary, the erosive wear rate increased initially with impingement angle, attained the peak and then decreased at still higher angles at the higher impingement velocity. The eroded surfaces showed more abrasion grooves at lower impingement angle and greater tendency of crater formation at higher angles of attack. In case of the composite, protrusion and fracture of the dispersoid phase was also noted. The composite also revealed less severe surface and subsurface damage than the matrix alloy.